Ask yourself why you broke up in the first place. You shouldn't need to ask us this. It's more your decision, and besides you haven't really given enough evidence...I'm sure someone will comment on what a mess this is. He still talks to you while married, he's still linked to her till the end of the year. Let's see, he was emotionally cheating with you while married. And now that he's separating, you two want to see each other. Him being in contact with her may or may not irritate you. You sound like the rebound chick, maybe you aren't, I don't know. But unless you have undying incredible feelings for him (feelings are overrated...eat chocolate or ice cream instead), then I would just drop it with him and move on. Unless you broke up for a reason like...heading in different directions in terms of career or something, and it can work out better, then I don't see why not. "You found each other again" yay, go for it. The only think I would suggest, is he not pay for her school. If he's so miserable, why would he want to continue living in misery being linked to this woman. This whole thing just sounds fishy.

Would you be okay with your husband calling and IMing other women to complain about how miserable he is to be in a relationship with you, and perhaps tell her that he has feelings for her?
If not, then this is not the guy for you... Because if he has done it to her, then he will probably do it to you.

It doesn't matter if his wife is Dracula and Godzilla combined, I consider it unacceptable to cheat (yes, I consider what he did as cheating). You say it was almost from the beginning of his marriage... And five years is a long time to cheat on someone. Five years is many, many, many chances to come clean.

Think long and hard about whether your truly want this guy.

Protect your heart until you find someone who can do it better than you.

I would wait a full year after the divorce before attempting to date him. I have a guy friend in almost exactly the same situation - married 7 years, separated last spring and are about to finalize. He and I hadn't dated in 10 years but he came back almost immediately and would have slept with me a couple of times if I had allowed it. Now that he's getting over the divorce and feeling better about life in general, he's toned it down and doesn't act as interested.

There's a good chance this guy just wants someone familiar and loving around him. Offer to be his friend but avoid being his therapist. Conversations should never be about the ex or the marriage . . .they need to be about regular stuff you'd talk about on regular dates. And by dates, I mean he calls ahead and asks to see you, not "Hey, wanna hang out at my place tonight?"

Sounds kinda fishy that he has been contacting you all this time. I am not saying he is, but he may be one of those guys who is likely to cheat. Also, to add to that, do you think you may have played an indirect role in him being miserable in his marriage? The fact that they are having a difficult time and he confides in you, and you listen to him, makes him wonder if he made the wrong choice. So he may want to date you now, or have feelings for you now because you comforted him during his time of need and he confused friendship with love?