would you consider this to be cheating?

when my boyfriend and his friends hang out together they text random women that sell sex content and ask them for pictures and also just chat with them.

i saw their group chat with screen shots of the chats and they have all participated in chatting with the women, even my boyfriend. they’ve been doing it long before me and my bf started dating. i confronted him and he deleted the app and said he would stop doing it but i feel betrayed and disgusted that he would even think it’s okay to do this while having a gf. he said i was dramatic and that it’s only a joke between the guys. would you consider it to be cheating? is it a reason to break up?