I'm a 20 year old man who was looking after my 11 year old brother, when he challenged me to a play fight. I thought it would be in good fun and accepted.
To my surprise, I get completely dominated and end up submitting 4 times in a row. The next day, he randomly pins me to the ground and wraps his thighs around my waist. Again, I submit but he says he won't let go until I say that "I'm his b*tch". He's completely crushing my waist so I just say it, but instead of letting go he forces me to say even more things like calling my girlfriend a "retard" and so on.
Eventually I can't breathe and throw up on the carpet much to his amusement. I've never been so embarrassed in my life. I don't know what to do, he's a lot stronger than me. I've struggled with anorexia in the past and this is him in the linked picture below, he looks a lot stronger than me:
https://imgur.com/a/ZhUwu
Since then he's been trying to boss me around and bully me, I can't even do anything about it. He's spat on me, choked me out, punched me etc. I want to bulk so I can protect myself but what am I supposed to do in the meantime? Just let him walk all over me? I need help, my dad isn't taking it seriously and I can't move out.