Trish, Joel sounds just like one of my younger brothers at that age. He would fly off the handle at the littlest thing and hurl abuse at anyone who tried to help him. Mum was at her wits end too and would loved to have sent him to Dad (my parents are divorced), but like you said, he was still her child and she would deal with him.

Does he have any strong influences among his friends? If there are, maybe he is just mimicking what he has seen them do with their parents.

If you have tried to talk to him to no avail, what sort of relationship does he have with his Dad, could he talk to him? Maybe he doesn't feel comfortable talking to you because your his Mum and you're a girl IYKWIM?

Another thing, is he just like this at home or is it school too? What do his teachers think?

I really wish I had something more to offer you, but I think perseverance and just letting him know you are there and will support him no matter what might help and also trying to get through to him what this could possibly do to your family (If DP leaves).

Take care Trish