I don't think the OP is being unreasonable to not want the MIL along on the holiday, and the MIL is not being unreasonable to want to go. The OP's husband is the one being unreasonable here. He has gone and invited his mother without consulting his wife. I would have been fucked off too.
@AlmostAJillSandwich
All these suck it up posts, have you ever actually had a difficult person tag on your holiday! It's not fun or relaxing, you know the person, what they're like and if you know they're going to be rude, demanding etc, then why just waste your money on a holiday you already know you won't enjoy?
Agree with this. They are fucking me right off!
And all the pious posters coming out with 'I am so glad I don't have a demon DIL, and mine is lovely and tolerant and inclusive' can bore right off. How dare you condemn other women like this when you know nothing of their relationship with the MIL, or anything about their lives. Plus, I am willing to bet your DILs don't like you as much as you are making out - not with your snarky, pious attitudes.
The husband is at fault here, and it sounds like he doesn't bother much with his mother anyway, and will most likely leave all the entertaining (of his mother) to his wife (the OP.) Most men do this, leave all the 'wifework' and dealing with the kids and in-laws to the wife. Don't even TRY to deny it! I agree with @L0UISA that the OP doesn't have a MIL problem, she has a DH problem; he sounds like a selfish, thoughtless git who puts himself before anyone.
@MeMeMeow85 you need to tell your DH that if he insists on his mother coming along, he will be going without you. Then you can have a lovely week on your own, and let HIM do all the donkeywork/wifework that he is expecting YOU to do.
I have to echo what some posters are saying that your kids are too young for a trip to Disneyworld. I have been with children several times, and any child under 5 y.o. struggled. It's not a little trip to see Santa, it's a full Disney experience; it's very hectic, it's very noisy, it's hot, it's crowded, there is a lot of standing in queues, and it's too much for infants and toddlers.
Plus, there are LOADS of things your kids won't be able to go on (or enter) because they will be too young and small. You must be batshit to take an 18 month old on holiday to Disneyworld. I would cancel the whole thing.
I think it's sweet he asked her. I don't get all this nonsense of family being ditched the moment a wife comes along
What a load of utter rot.
@Greatduckcookery
Incidentally, I do think Disneyland works best if there are more adults than children.
With another adult at least the OP and her DH can go on rides together too while grandma watches the kids.
So basically, it's not a holiday for the parents and kids then. It's just a holiday for the parents. The OP and her husband may as well go to Disneyworld on their own and leave their kids with the MIL back in the UK.
@hmcAsWas
I don't think its weird not to want to go on holiday with your PIL even if you have a good relationship with them. Equally I don't think its weird for PIL to join their dc and their partners and children if all parties are happy with it. However it is weird of your dh to unilaterally decide something like this without discussing it with you first. Does he have form for being inconsiderate and ignoring your opinions? I would be furious.
I agree with other posters - salvage the situation by deferring the Disney holiday for a couple of years so that you can withdraw the offer without actually withdrawing the offer.
Best post on here. The OP needs to cancel the holiday now, and arrange something in the UK that her MIL can come to as well, and re-arrange Disney in around 4-5 years, and have it out with DH for asking his mother without consulting her.
For all of you that agreed with the OP, just remember one day you will be a MIL too. Life is a circle and when it comes round to each of us it can be a real bitch
You sound like a controlling and bossy MIL. Bore off.