My girlfriend loves to make me a gag in front of her friends

I'm gay and have a girlfriend and I don't understand why, but she loves to make me look stupid in front of her friends. These were her college friends and they graduated with masters. I didn't go to college. It wasn't in my dads budget, but my dad did everything for me as a single parent and I am forever grateful. She will ask me questions in front of her friends that she knows I don't know the answer to and when I say idk or get it wrong they laugh at me and she expects me to laugh too even though I tell her it bothers me. She makes fun of how I pronounce things too. I have a bit of a southern accent and a lisp. She constantly teases me in front of her friends about how I talk. She also refers to my father as a Hick even though I've told her not to do that. I grew up in a trailer and poor and she continues to make me the butt of every joke in front of her friends. Because she does that her friends don't take me seriously and think I'm stupid. Shes pretty much presented me as trailer trash and when I tell her it upsets me she says I'm just being pissy because I never got to go to college and she did and that I need to stop being so jealous. I'm not being jealous, I'm just tired if being used as a prop for their entertainment!