This sounds really serious to me and not something you should be afraid to discuss
It sounds like you love your mum but sad to say she's neglecting you too by allowing it to happen. She's probably lacking the courage to stand up to him and to cope with life on her own
You must talk to someone about this.
A good start would be someone at school or maybe your local GP who should see any injuries you get and they can alert child services again
You are old enough to speak up for yourself so don't let it get covered up.