I assume he did not marry that girlfriend. I know there are many thoughts running through your head, of anger, revenge, hate. BUT you should feel greatly relieved because he left you. Would it have been better if his girlfriend had his baby and he didn't leave you. Isn't it better not to be married to such a person. So, clear your mind of those thoughts so that you can move on with your life instead of mulling over the past and not moving on. After all, what future does he or his girlfriend or even the baby have? At least yours is open and you are free to move on. Do it and don' dwell on the past.