Single mother asking about karma?

So my ex left 9 months ago when i was 4 mths pregnant, and i've seen him only once when he came down to meet our daughter (when she was a little more than 3 months old). I just found out he has a gf and even took her to meet his mother, when it took me 6 mths to meet her. Its finally hittin me that he doesnt love me, but i cant understand how he can not care about his daughter. He has never helped with any expenses and calls like evrey 2-3 weeks to ask about her. I just wanna know if this has happened to anyone else, and if so, did the baby's father ever regret what they did to you and/or your child. It hurts like hell cause when my baby wakes up in the middle of the night, i wonder if he's with her, and cuss him out because i didnt make our baby alone and he should also be going through what i am. It's so much easier for them to move on after they dump everything on us cause they dont have to be a parent 24/7/365, we on the other hand have our lives changed completely. I believe in karma, but i wanted to know if any of those other guys that do the same actually get it afterwards. Any experiences or advice?