Living with elderly inlaws with dementia?

due to financial reasons elderly inlaws with dementia are living with us. it has added alot of stress to our lives, seeing that we have only been married for almost 2 years, we have 7 kids only one at home and one grandchild we are raising. now in our over crowded home we have them and it has caused even more stress and sometimes i feel his mom is actually trying to break us up. my husband thinks im being not very caring and i believe he is not being very understanding. it is too much for me and when she plays up to him like today she acted like she could barely walk in church today and purposely left no room for me onthe pew to sit. come home and she is walking fine. im sooo stressed that and the holidays.