Picked my 5 year old up by the head

Guys my ex SO and I were trying to work it out I’m 29 weeks pregnant. Well my 5 year old boy and I went to a birthday party Sunday then after the party we stopped by at his house to say hello. And it was all a fine but then my son wanted a family hug and a kiss and he my 5 year old is every hyper and gets a little crazy sometimes so he’s harder to control but no it is not an excuse, so my 5 year old asked him for a kiss but then the 5 year old backed up and my ex SO grabbed the back on his head then grabbed the front of his head and picked my 5 year old up by his head. I grabbed him immediately and asked why the fuck he would pick a child up by the head. He could have broken his fucking neck. He said well he was holding on to my arm so I thought it would by fine. Then said well he’s always rough with your or me and stuff so I want him to see what it feels like. I was in shock I honestly thought my son was gonna have a broken neck. He’s so rough with my 5 year old. I understand put him in a time out or send a child to their room but he always took it to the extreme and now i just don’t feel right having him around my son I don’t even think I would consider fixing it with him. I just wanted to vent and throw that out there.