AITA for telling my husband to get rid of his childhood cat?

My boyfriend and I have lived together for 2 1/2 years. He brought his childhood cat with him since she wasn’t being taken care of at his parent’s place. I have known this cat randomly vomitting up food sometimes. The first year we moved her she was fine, but now she has started doing her business not in the litter box. This had been the third time she pooped in our shared closet, but the straw that broke me is that she had laid on top of me like she does almost every night, only this time she decided to vomit on my head! I didn’t get any sleep that night. The vet said she has a sensitive stomach and we should try a senior diet. We have, but she still seems to vomit. She’s 12-13yrs old.