Wait wait wait, isn't the bigger problem here being your fiance? I mean, he's the one who decided not to defend or stick with you when his sisters kept you away on the cruise. Isn't he also the same person who hasn't done anything to ease the tension/beef between you and his favorite sister? And why did he tell you that Katherine the sister said don't marry you? The man hasn't acted like you are his partner. Why are you overlooking the biggest red flag here and instead focus on the sister? Do you honestly believe if you have your way with the wedding and if the sisters stay away you marriage will be all rainbow and sunshine?

I think you need to sit down with your future husband and ask him what the future is going to hold for you, if you will always be second fiddle to his sister. He needs to tell his sister to pack the attitude away and he needs to come clean if he knows why his sister doesn't like you, or he needs to find out because no-one needs to be dealing with this highschool level BS their entire lives. ETA- the wedding is the least of your issues right now, you need to deal with the fiance problem before you tackle to wedding problem.

You have a fiancée problem, not a future SIL problem. If he's not siding with you now or putting you first now, he never will. If a wedding is more important than making you, HIS future spouse, happy, then it won't ever be.

Honey, dump THIS A*S WAFFLE NOW.YOU WILL ALWAYS BE BEHIND SISTER, HIS Nieces Or Nephew. Go find someone who really respects and loves you

George needs to grow a pair.

Where is the poll option of not getting married? She needs to run!

Girl, why are you still planning the wedding? Your husband is meant to have your back in everything. He's already shown that he won't, and worse, he'll pick fights and blame you for other people's rubbish. For pete's sake, he left you alone on a holiday because "he was there for the kids" not you. There's more red flags here than at a chinese military parade. Get out asap.

I won't say dump him, because I know from painful experience how stupid men can be, but you need to sit him down and point out how wrong he was for not sticking up for you on the cruise. A counselor may be able to help with that. After that, if he sees where he was wrong, and understands that he needs to change his behavior, invite his sister to the wedding, since he wants her there, but only with the understanding that if she misbehaves he will immediately shut her down, and not leave it for you to deal with.

Or....don't marry the jackass.

My current husband and I had a VERY small wedding (Justice of the Peace, my best friend and her husband, his son and my son) because I have a horrible sister. Horrible as in she chose to come out AT HER OWN MOTHERS FUNERAL. I think a small wedding is a lovely thing. We wound up doing the reception before the actual wedding and everyone had a great time.

BP and Reddit are often quick to 'dump him and run!' or divorce, but before you go there, counselling (as others have suggested) would help clarify things. Why didn't he stick up for you? Why was spending time with his sister's family more important than you? Why doesn't she want you to get married? What will happen the next time she excludes you? These are serious questions to ask, because the answers will help determine if you want to be part of this family. Be strong and stick to your boundaries because these are going to be difficult conversations. You can do it. Good luck! Edit for grammar.

Honey, you are marrying your fiance and his sister. Apparently he can't make any decisions against her wishes. He doesn't stick up for you with his sister? There will be three people in your marriage. Good luck with the red flag parade. You're gonna need it.

I'm not entirely sure you should be marrying this person, OP. Doesn't seem like you and him (plus his family) are compatible. Perhaps have a nice long come-to-Jesus talk with him as some of my fellow commenters are suggesting, but it doesn't sound like being married to this man is going to be a pleasant experience for you, long-term.

If you let his family dicate things now, you'll never be happy. If he won't stand up for you now, he never will. Run, and don't look back.

ESH. Future SIL for trying to drive a wedge, George for abandoning OP because his sister said to when he knew the deal with the cough. Her hold on him is creepy. But OP is TA as well, not for the change of wedding plan, but for not being direct with George. Without a good explanation George will be resentful (it's perfectly okay to not want a big wedding, but that needs to be a discussion and joint decision). If this isn't nipped in the bud now, future SIL will control the lives of OP and George forever.