I'm sorry you feel like a burden, I can definitely relate

Maybe you could try coming up with something that can make you feel useful to someone? Like with your cats... You can try doing something that helps others, like volunteering somewhere.
At least this is what helped me. At the end of the day I know I've done something good. Even if I'm not essential to anyone, if I was able to make a brighter day for someone I feel a little better about myself and my existence.

Take good care of yourself