I'm stuck in a very tough situation, please help?

Me and my girlfriend have been dating for 8 months now, she moved in with me the 2nd month, not because we were fast but frankly I couldnt stand how her mother and brother were treating her, so we've been living together for 6 months. As time go by our relationship was great, and I did all I could to be a great boyfriend and I am, seeing that her past boyfriends were s(Cheating, Lying etc). But as of now we're in a really bad place I frankly cant stand her, she has an attitude more than often and we fight about trivial things. In order for me not to say anything I'll regret, I stay quiet when we argue but she just cant and she wants to talk and continue which makes me more frustrated even though I've told her its best to leave me alone so that I do not say anything I regret. This week alone her attitude and our constant bickering has frustrated me to new levels. Just today we got into an altercation, that basically ruined my day and as of now we're not speaking to each other. I am the first one to admit that I have a very short fuse and little tolerance for anything, so I want to break up, but heres the thing, we're both in college and I'm her ride to school and work, she doesnt drive yet, and if we break up obviously she'll have to go back to her mothers house, which is a living hell(She was depressed and needed prescription when she lived there, and the happiest shes ever been living with me,)she said if we ever broke up, she'll leave even though its terrible at her moms house because itll be too heartbreaking staying with me. But staying with her brings newer problems and arguments and like I mentioned earlier, I have a low tolerance for bull,I'm tired of always being mad and always fighting, and sitting there quiet while she has this attitude, whats should I do?