I'm worried about my ex boyfriends abusing his son

I reached out to my ex boyfriends 18 yo son to check on him. My ex boyfriend abused him so bad when we were together... I made excuses like his son was being disrespectful and why doesn't he leave if he's 18. He's in High school still. He beat his sons face into a wall repeatedly and another time when his son did absolutely nothing, he beat him and held a gun to his face. I messaged.I'm asking if he was safe and I hope he's doing well. I know his dad only spent one night in jail for.the gun incident. He replied back hours later saying nothing HS happened that he isn't already used to. I told him he shouldn't be used to abuse and he said he doesn't care anymore.... And whatever happens happens... He doesn't care if his dad kills him! Idk how to help. I just feel so bad for him... He has no where else to go... I would offer him a place but that see!s inappropriate...

Edit: With the gun situation I called the police and dumped him.

Edit: He's 18! Its not like I could have called cps!!!

Sorry I didn't noticed I put I feel bad for me. I meant I feel bad for HIM