Does he have a right to get mad about us still being friends with his ex?

My husband has a really good friend he has known forever his friend got a girlfriend and me and her became really good friends he was with her for 3 years.

She ended up breaking up with him for good reasons he became controlling and demanding and started treating her less like a partner and more like a maid. He would call her horrible names like slut, bitch, and whore. She would tell me about some of the stuff he would do and is was way out of line of normal.

Me and her continued our friendship even after they broke up. She got a new boyfriend and me and my husband went out with them a few times (restaurants, amusement parks, bars). My husbands friend “the ex” found out I’m still hanging out with her and is pissed and trying to say it’s wrong for me to hang out with his ex. Then he must of saw a picture on Facebook ( his ex Facebook since we don’t have one) of all of us me, my husband, my friend, her new boyfriend at Disneyland and he blew up on my husband calling him a bad friend and what we are doing is wrong. He even had the nerve to say if me and my husband split up he wouldn’t keep talking to me. ( I’m thinking ok that really makes me want to stop being friends with her yeah right). My husband told him that she is my friend they have been good friends for 5 years now and he not going to stop that. He was trying to tell my husband to make me stop being friends with her. He is getting ridiculous and will get drunk and come over yelling and screaming about us still being friends with her and then apologize the next day when he is sober this has happened multiple times. Now my husband is getting to the point where he doesn’t even want to continue his friendship with him. What’s your opinion does he have a right to get mad about us still being friends with his ex?