Please help, I don't know what to do

Sooo, this guy (who I'll just call Jay) that I've been dating, moved in with this ex gf (who I'll just call Lee) a couple of weeks ago. They were fine and dandy until I started coming over regularly, and Lee got INSANELY jealous. They were constantly fighting and she's tried to kill herself multiple times because of it. Jay was trying to help her out and kept calling her dad, who hates Jay, to get her the help she needed, but Lee's dad basically blew her off. THEN I stayed the night lastnight (which we should have just stayed at my house, my parents like him. well, liked) and Lee kept throwing temper tantrums because I was there, and Jay had to keep checking on her to make sure she wasn't hurting herself. When I left there this morning I just had a feeling something bad was going to happen, so I tried to make Jay leave with me, but he didn't. Like not even twenty minutes after I get home I get a text from Jay saying "I broke my hand, come get me. I need to go to the hospital" and he keeps sending texts saying he messed up. I get to his apartment and he has his bloody hand all wrapped up and he's freaking out. I told him to calm down and that I'd take him to the hospital and he has to tell me what happened. Apparently she was ordering something over the phone that she was going to use to kill herself, and Jay broke her phone so she would stop, and he said after that he blacked out and when he came 'round Lee was crying and running out of the door and his hand was all sorts of messed up. I asked him if he could remember anything else, because I'm assuming Lee egged him on (she has one of those personalities so I know she did) she must have pushed him, he probably hit her, and then punched something else that broke his hand. Now I'm his only friend, I took him to the hospital, Lee's Dad had the nerve to say something smart to Jay as he walked by so I had to pull him away from the door so he wouldn't do something else stupid. I stayed with him as long as I could, calmed him down a bit but then a cop came and took him downtown and told him he'll be in court tomorrow. Jay gave me all his keys and the money he had on him, and he was saying he was so sorry for dragging me into all this, went on about how he didn't mean to hurt her at all, and said he understands if I don't want to be friends with him after this. BUT THIS IS WHERE IM DUMB AND I STILL HAVE FEELINGS for him. I know he's a good person, I know he is. All of my friends said I should just stop seeing him but I just can't walk out on him like that, I'm the only one he has left, and I still want him in my life. I think I love him. And I'm so worried about him. I just don't know what to do anymore, please give me advice.