Do NOT get involved with him right now. Tell him he can call you 6
months after the divorce is final, and not a minute earlier. Then move on with your life.
Your presence in his current situation changes the dynamics of what he is going through. It is complicated, but you need to be aware that most of the changes that you cause (unknowingly!) are
not conducive to the two of you having a successful relationship in the future. Read that last sentence again, it's important.
This is one of those times when you need to let your brain overrule your heart.