Is my boyfriends anger towards my daughter justified or did he overreact

I have two kids that are 20 and 15 and my boyfriend has one child who is 17. My daughter 15 and my son is 20. His son is 17. My boyfriend asked was his son's friend coming over for the weekend because he's here every weekend. His son says "No. Fuck him!" He asked what happened and his son said "He can go fuck himself." My daughter says "The girlies are fighting." My boyfriend's son didn't care that she said that. My boyfriend gets angry and yells "My son is not fucking girl!" His son said "Dad chill." He goes "No! He's not a fucking girl. Don't call him a girl." My daughter says she wasn't saying he was a girl. It's just a thing she says. He cussing at my daughter and says "Well don't call my son a fucking girl or I'll let him call you fat bitch." I told him not to ever talk to my daughter like that again. She cried. He said he wasn't saying she was a fat bitch but he will allow her to be called that if I don't do something about her calling his son a girl. All while his son does not care. He's on his phone and telling his dad to chill out and he doesn't care. So my boyfriend said we are all assholes and went out to pout in his car. This seems like an extreme overreaction when his own child didn't care.