Life decision between maintaining my sanity or reaching my breaking ponit everyday.?

(More difficult then really is) long story short my parents split beginning of this year. Moms got a new bf ever since then she seems to be a bit rude,mean and distant im the youngest so i get it more since im the first to see her when she gets home. Me and my older sisters decided she was bipolar (and were not overreacting).When shes with her bf shes all nice and when its just us we can never have a convo without it ending in a fight. My situation is my sister is moving out so its just me and i know me and my mom are gonna clash more especially since shes gonna move in with her bf my the end of the year( i know shes moving way to fast). So i already know that were gonna argue we got in a HUGE fight i stayed with my ant for 2 days and didn't talk to her for a week and my sister said if i wanted to stay with her a year in san fran, im in my last years of High school. For the record my mom wasn't always like this she was awesome, she always told us