Before issuing an ultimatum to him, set one for yourself.
It does no good to draw a line in the sand and back down. Be prepared to back it up if you do.
I'm sorry about the business involvement, is there a contract btwn you regarding that?
Glad you're seeing a lawyer. If there is a contract, definitely bring it to see if & how you can change that situation.
One way to work on not wanting contact with him is to replace it with wanting more contact with you.
You go deep sister.