And this is where steemit comes to the rescue, I'm not sure of your age currently but it sounds like it's time for you to get out of the house.
A job, and then move out. I know personally I become depressed and reclusive if I have no interactions with the outside world - we are social creatures and despite the fear you may have about venturing out on your own, staying in the current environment is bound to hurt you more than this option.
Both emotionally and physically it seems, also I believe mother's and daughters are bound to clash to some extent. Like father's and sons will because essentially the parent has created a better version of themselves and it's hard to see a younger version of yourself because you don't want them to make the same mistakes you have. Albeit, most forget that they wouldn't like the treatment themselves at their age.
Also if your mom really chooses him over you despite everything maybe water is thicker than blood in this case.

Also before someone says but look at her other posts! Their irrelevant to the situation, but I get the concern.