You didn't FU. I highly doubt grades would've made the situation any better. (incorrect term but this matter is way above your age grade) I don't think you can really do anything given the financial situation and stress your parents are facing right now (likely you could consider working after highschool or do part time jobs to help out) but she's just taking things out on you and your sister. It sucks, but most people would naturally lash out (close people usually) when they are extremely stressed out. Just know it's not just about your grades. Try to reflect and improve in your studies for your own future..