"Doing the right thing"? What exactly would this "right thing" be. OP should ask his brother. What possible good outcome could this absolute b***h of a woman have been aiming at?

The woman obviously thrives on drama. But more importantly she illegally obtained a medical test on OPs daughter without permission from the child's legal parent. If I was him I'd pursue that because hus brother seeing him seriously wrong she is then maybe he'll see what a mistake being in a relationship with her would be. Shes a walking advertisement for red flags

compared DNA to brother's who knew she was adopted? so WTF? surely he would have told her or did she take his DNA without telling him? And then he stands by her - just cut them off until she's gone!

"Fiance, can you explain something to me? OP - your brother - was showing me a picture of Lily's mom - what's the story there?' 'Oh, Fiancee, OP adopted Lily after Lily's mom and dad were in a tragic situation.' 'Ah, thank you for letting me know!' End Scene.

NTA for laughing in her face. I would actually press charges; it's illegal to do a DNA testing without consent. I would also stay away from this woman at all cost. The brother is in for a very long marriage if he doesn't wake up now.

The fact that she did it in front of the child, is child abuse. It's already horrible that she did it in the first place and not in a "I'm so sorry to tell you, but I need you to know that your wife was cheating" way, but in a way that suggests she wants to hurt him or she wants to be right. That's already horrible. But the fact that she did it in front of the child in question, is downright emotional abuse and she should never be around the child again.

What should his response have been that would not have embarrassed her!? There is none. She did it to herself.

She went way out of her way to supposedly save you from the misconception that Lily is your biological daughter. She clearly did it without any conversations with your own brother because aha...check me out, the only hero in your life that has your back (in her mind). Not considering the child or even the brother who she should have shared everything with, she went ahead with her heroic scene..... brother would have told her the facts if she ever bothered to ask, Get it? She wants you and is manipulating her way into position of trust in your life, regardless of anyone she hurts in the process. I hope the brother does the maths before it's too late.

SIL might be having her own affair.

The brother has got a shock awaiting him; this will not be the last time she does a petty disgusting thing that's none of her business in order to deliberately cause hurt and chaos. Imagine if that little girl hadn't known she was adopted? That woman is evil

Performing a DNA test on anyone without their permission is illegal, as is doing so on someone else's child. That was an assault on a child and Op should involve the police. SIL should be arrested and charged with assaulting the child.

SIL could’ve simply asked about the picture of OP with Lily’s parents, and how he ended up as Lily’s dad/guardian. She would’ve gotten logical answers that should’ve been enough. It almost sounds like Lily’s parents had made OP her godfather, or he simply took on that role, so he would take care of her if something happened to both of them. What’s so damned difficult to understand about that? Life is not like some crappy soap opera or staged Reality TV show, ffs. There aren’t elaborate and unrealistic storylines, there’s just s**t that happens and we just have to improvise how to deal with it and hope it all turns out OK, because we’re not living a story that was created with issues that have solutions already pre-planned. We’re experiencing real life. So there’s no need for soap opera or spy story type of espionage to secretly obtain someone’s DNA without their knowledge (cops do it with a search warrant, regular people don’t have such authority) and have it tested to find out a child’s paternity. SIL is living in la-la land if she thinks this is proper behavior in real life. Bro is just stuck in the middle. He probably agrees with OP that it was really out of line for his fiancée to do that, but he also has to live with her, or at least spend a lot of time with her, while she rants about OP’s reaction to her unwanted and improper sleuthing. He’s just trying to juggle living with both sides and maintaining some semblance of peace, while being the poor monkey in the middle of a situation he didn’t create.

There is an update about the post on Reddit. The mans brother tricked SIL into believing that he was in a relationship with the girls mother, and that he truely believed the girl was his own biological child. Long story, here's the link: https://www.reddit.com/r/AITAH/comments/1f5zjc9/update_my_brother_lied_to_my_sil_about_everything/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button

She's a FIANCE not a SIL, ffs. I'd keep her far away from my family, what a cow

You're brother & his fiance will have a VERY TOXIC relationship. Call it off! Congrats to you for a adopting this precious child. God bless. 💗

Please, the woman is a trouble maker with a big T! What if you both were married and you and Lily's mom had to use doner sperms to conceive? Being a outsider to the family the fiance' would not have been party to that. She was out to make herself the center of attention to prove your daughter was not blood. I cannot imagine if she and your brother have children hoe soon before she insists her children benefit from family generosity becouse they are "blood " related..Her children should always come first with the grandparents. She is a real witch and future loose cannon. What bussiness is it of hers how Lily became your daughter. The fact that she and your brother do not see what she has done is wrong would signal to me someone to be avoided at all costs.she is poison!

I would have gone off on her. Firstly, you can press charges for her illegal actions. She had no right, period. Had she asked , you would have stated the details assuming you wanted to do so. Regardless, you can call Lily your daughter no one has the right to tell you who , what ,where, when, or how. That's your prerogative. You are her guardian and your job is to protect that innocent child from, who so ever is a threat, mentally, emotionally, physically, and any other way you feel the need to protect her.

First what you did is admirable, not many people would do this, and raising a child is not easy. What your SIL is just a little, unhappy, ugly woman who put should stay out of your business. You have every right to be angry with her, what you build for your daughter, she tried to destroy in seconds without any concern. That says a lot what person your SIL is. Hope you can repair the damage and wishing you good luck.

Goodness - what a horrible, interfering, potentially backstabbing crazy a*s b***h that SIL (to be? I wasn’t sure as the poster said she was a fiancée…). If the brother defended her abhorrent behaviour, all I can say is I guess they deserve each other, but the poster guy should decide to distance himself and his adopted daughter from their negativity.

What a sick, twisted b***h. I can’t even think of anything else to say. Asked my SO and her first reaction was, “And the rest of the family was ok with what that sick b***h did?” OP should consider distancing himself from the lot of them.

I see a pure trouble maker here. If they actually marry it will be life long drama for this family!

This is weird. If SIL used her husband's DNA then he must have known what she was doing. Why didn't he tell her about the adoption? She didn't discuss the results with her husband before making a scene. Both the brother and SIL sound like they should be avoided like the plague.

The article states, "Most commenters didn’t agree with the sister-in-law’s behavior." I'm wondering, who in their right mind would be cool with this? The SIL is an odious creature!

So, how much did it cost to get your brother stitched back up? I know my brother would be expecting an a*s whipping and realize that was going to happen speaking to me like that. He never would, nor would I he.

Yikes.

The brother was as bad as his girlfriend for going along with it by giving her his DNA. I would steer clear of them in the future. She’s probably the type who will make constant jibes towards your daughter. Evil bstrd is what she is and your brother isn’t much better

Brother is a wussy to think she did no wrong. Cut ties from both.

Since she was studying the portrait of you, Lily's parents and then somehow decided she needed to test the child and HER HUSBAND, I think she saw some form of family resemblance to him, not to you. Probably hoped her hunch about her husband not being the father would trigger you being the father. Sometimes drama queens get too deep into their own lies. She was most likely looking for answers she hoped wasn't true and then decided to go the way of hey, your daughter isn't yours! (Thank goodness my husband isn't her father either!) Type of stuff. But sounds like this woman has some very deep seated issues overall! I'd for sure not allow my daughter around her anymore.