I am so very sorry that he's acting out. He has no control over anything in his life, so he wants to control you and your son right down to what he eats.
Don't believe a thing he says about not serving you at work. Some of them say that and then turn right around and do it. My papers came in the mail several days after Christmas with nothing but one cents stamps all over the envelope. How's that for a lawyer's office?
He really is trying to justify what he's doing, but it's falling on deaf ears because you know that you are doing the best you can dealing w/everything.
Think of the ow this way...right now, it's a fantasy and one that both of them have been dreaming about. The sooner that they are together all of the time, the sooner they will see the flaws and warts of their situation. She's not getting a prize by any means, i.e., he's miserable and he's a "used" model. You had the best of him and now she's getting the shell of the man he use to be.
Take care of yourself and your son. You've done the best you can w/what you've had to work with. Continue moving forward.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.