hun, i've been with my bf for 2 years, we are 4 months into our 3rd year. My family DESPISES him, and his family would LOVE to see me dead on the street. And like you i thought his family really liked me, in fact they treated my boyfriend like a human being just so i'd think they were good people. Because I don't speak spanish, whenever at their family gatherings, they'd talk s**t about me right in front of me in Spanish because they knew i couldn't understand. It's caused alot of problems for us.
One thing we do is we try to talk to each other every night. When I get my A.A. degree in a couple years, he and I should have enough money to get our own place, and when we do, we aren't letting either of our families get involved in our relationship anymore.
Don't leave her because of her family. Do you think she's the one for you? If it wasn't for her family, would you want to stay with her? If so, stick it out, and just be polite with her family, or don't even associate with them.