couple of thoughts....

I realize I don't know you and your situation very well but a few things pop in to mind....

Are these her pets or yours? If they are yours, then you don't have a right to force her to care for your pets - so as hard as the idea may be, rehoming might be the best plan for one or more of them. Being a young adult, going to school, working, and supporting so many animals might be overdoing it.

There's a book called "Boundries" (sorry, don't know the author), that might be a good book to read.

You're only 19 but have been forced to grow up too quickly becuase of your home life. Don't let your mom drag you down. You can be kind and respectful, but you don't have to get sucked into the drama.

I wish you the very best of luck during this difficult time.