Hit your boyfriend? I understand you feel badly that he will be alone and you want them to get along but hitting is abuse! Drinking too much is not an excuse, he could of caused an accident, you were in the car too. He needs anger management as well as AA. It is not your job to clean up his act. He is an adult and needs to take responsibilty for his actions.
You sound like I did when I made excuses for my exhusband. Your father needs help. I would tell him as much and make it clear he would not be seeing me again until he got it. I understand you feel bad for him, but calling him is safer IMO than visiting for now.
You have a man that has stood by you through this, even been hit by your father. I wouldn’t put him in this situation again. I would be putting my love into protecting him and doing what is right for everyone involved. I wouldn’t see him again until he gets help.
Maybe a christmas without you, will be the motivator he needs to get the help. You can still call him.
Good luck.