My mom acted basically the same way for many years when I was a younger teen (12-15) and she still has outbursts of the behaviour now (I'm 17). I never delt with it the way I probably should have. I think you should probably keep acting the same way, because freaking out on her will do nothing. Maybe move out, if you can.

Sadly, I've been classified as clinically depressed and bipolar and to be honest, without meds it's no fun and even with meds it's no fun all the time. It takes so long to balance out your mood and your emotions (and meds) that it wears you out. It's frustrating and upsetting most of the time and to be honest, I've snapped on quite a few people very close to me and may have even lost a boyfriend because of my 'craziness' (good riddence tho). Just be paitent with her and try to understand how she feels I'm sorry bud, I know I've made my family's life a living hell I can't imagine what a grown women who you're supposed to trust and rely on has done to your's.