Big fight,!!!!

Ok so me and my partner live with my dad at my step mother for past few months now until we try and find a house, my dad and step mother work in the city so I asked her if she could take a phone in to get fixed for me , because me or my boyfriend don't have cars, so she came back from work this morning to take me to my doctors appointment, in the car I asked her if she took that phone on for me (I'm paying for it to be fixed) anyway she goes no I'm not doing it I do everything for everyone and just starts losing her shot saying everyone walks all over her an use a her and all this so I just lost it , I just couldn't believe how she was, saying I'm bout to have a mental break down and all this, the only reason I ask her to do a few things for me is because I don't have a car or a way to get any where because I live in the middle of no where with no buses or anything, so I have a history of being in mental ward and self harming and depression, and she's going on how she does everything for me an my partner and says she pays for our meals n all this, me and my partner are out of work at the moment, and we r earning 600 together a fortnight we do all our shopping when I can get to the grocery shop. And pay electricity while we r living her, I can't live with this shot anymore because I will end up harming and going in to shut down mode and depression again.!!!! I won't say sorry because I don't feel I have to! How do I go about this , ?? She carrys on how she HAS to stay up till 1 am and get up at 6 am for work (she does NOT have to stay up till 1am) and she only works 2-3 times a week and not even full days! Nothing is ever good enough for her and I have had enough !!!!.