K, I'm going thru this as I write. I left my AH almost two months ago, did all the "codie" things to like pay half the rent, leave groceries, furniture etc. He'd been alone a week and was introducing his "new" girlfriend to my friends in the building. I've since found out that he has been seeing her for years. I had no idea.
But, that is not my problem. It has been very painful but I'm having good days now. I have developed a circle of supportive friends, taken up yoga, "nesting" in my new home, all positive things for ME. The days/hours that I think about him, what we had (separating the reality with the fantasy) are becoming less painful. I'm not obsessing like I did a short time ago. I've also realizing that this is the best thing for me - I believe that now, in my heart and in my mind.
Be strong for yourself and your new child. You are doing the best you can.