hi and welcome,
do I really need to tell you that you have a 12 year old who is learning about life from you? And from a raging drunk? And he's hiding in his room? Worried about his mom? Wondering if you think he's important enough to protect?
This sounds so severe, but my heart breaks for your child. You can still be this man's friend/rescuer/girlfriend if you want to, but can you at least get him out of your house so your son doesn't have to bear the consequences of your decisions?
You ARE smart. If you weren't, you wouldn't see what's happening in your home. ((hugs))