Animal-related guilt

When I got Bill, I also got his two cats (littermates, about a year old). I've never been a cat person, but we seemed to reach a place of co-existence. When they had problems, I did research to figure out how to fix them. I don't think of them as my cats, but they made Bill happy so I did what I could to keep them healthy and content.

Now I am actively disliking them, due to their puking/shitting/underfoot issues, and we are getting to the point where I don't think Bill is liking them very much, either.

( Whine whine whine. )

Any brilliant insights or words of wisdom from you all?