Emotional Affairs

My husband and I are separated. Married 25 years. He was not happy and decided to move out. We have worked on things, but nothing has helped. He is also a victim of childhood trauma, sexual, physical and mental abuse. That causes a lifetime of scars.
He developed an emotional affair with a coworker about 18 months ago. Although he claims nothing physical ever happened, he is still very much connected to her. As he has told me the emotional affair was not what caused the issues in our marriage. The issues were there before the emotional affair. I agree, but what he cannot/will not see is that as long as he is continuing his involvement emotionally with this coworker, there is no way for us to try and heal our relationship. Couples therapy did not help especially since he lied about still being involved with her.
She has been going through a divorce as well. That started about 8 months ago and she is still not divorced, but the timing is suspicious.
I truly want to try any last ditch effort to save our marriage, but can't seem to get him to understand his attachment to this other woman will not help.