From the convo you remind a TON of my sister in-law. Incredibly helpful and generous person, willing to do whatever possible to help people. HOWEVER, she seems to mainly attract people into her life that are only interested in one-sided arrangements like this and are supremely ungrateful.

Be nice to people who appreciate it. You will never (and I mean NEVER) do enough for someone like this to appreciate it. Its just not how their brain is wired. If you bent over backwards and did everything they asked then you're teaching them that they can walk all over you and they will do it again, and they will keep doing it.

I remember hearing a saying once that went something like "you can lay yourself down for people to walk over you and they will still complain that you aren't flat enough."