My mum and stepdad said they can only have a baby with my help

My mother and stepfather want me to donate my
eggs to them so they can have a baby. I declined
to do so. But they have been pushing and prodding
at me about it and won’t take no for an answer.
Now my grandmother is calling me a "home-
wrecker," saying that my mother and stepfather will get divorced if they're incapable of having a child.
My family refuses to go to a donor outside the
family because it wouldn't be "their" child, and they
say my genes are 50 percent from my mother.
They also won’t consider adoption because they
say "those kids are disgusting and messed up." They plan on having my eggs harvested and raising
my child as their own. I am a university student
who lives at home, though lately I have been
crashing on friends' couches in order to avoid going
home because the situation has gone from hard to
ridiculous. My family has been controlling and emotionally and verbally abusive all my life, and
until recently I didn't realize that normal families
aren't like this. I have no way to escape because I
can't afford to move out—I have a job that doesn't
pay that well, and I'm also a full-time student. What
can I do?