My mom abuses me emotionally and verbally. What should i do?

I am 19 years old and i have my own place and i am in college and i have a job. But whenever i bring anything up with my mom she yells at me and makes me feel like i am nothing. In the past my mom cheated but my dad forgave her, and now she is sick with fibremyelga. Now shes always home and same with me when i am not working, and my school work is all at home, so i spend alot of time over at my parents helping out. I know that if things arent good that i should go home, but it feels wrong at times because she constinly complaining about when i am there. My whole life i was the child that they cared about most and wanted to succed, but now i am old enought to take care of myself and they have my brother who is still in high school and is the worse, its almost like they stopped being a parent. I dont like how they are. My mom has this thing where she tells the truth all the time but if we say the truth we get in so much trouble. What should i do?? Someone Please tell me.