L.
I feel for you! Maybe you could have the birthday party at a friends, relatives that are close by or McDonalds, Mr Gatti's, etc.. You have a lagitimate excuse to not have it at your house. If any one asks why you're not having it at home, beccause the house isn't ready for company. If they don't understand that, then they're not too supportive. If you have paint and other things laying around, it's not safe for children especially other peoples children. Take the stress off of yourself and have it at McDonalds where all you have to do is pay for it. My daughter does the parties for the McDonalds she works for and did my son's last birthday party. All the kids had fun.
At least is sounds like you have the support of your husband. That helps a lot. Maybe your FIL doesn't need to help anymore, unless your husband lays the law. As for you MIL, it sounds like special occasions are the only time you and your family really need to spend time with her. I don't know how you've done it for this long.
Good Luck! I hope I could help at least a little
M. B
Married, 4 kids, 17, 15, 11 & 5. Stay at home mom with MS and Fibromyalgia. I live in Converse, TX