Maybe I moved on too fast?

I find myself crying about my ex even though he left me almost 3 years ago. I am in an entirely new relationship since he and I broke up but I can't seem to get over it and I feel bad. After he broke up with me, I found out I was pregnant and when I told him he asked how do I know it's his, and showed no interest in even trying to help or be involved. He insisted I abort which of course hurt me even more. Our relationship wasn't the best but I would have done anything for him and even begged him to stay. I guess I cant get over all the promises he made but were broken Idk.... I even got depressed when I saw he got into a new relationship. I'm not sure why I can't let this go and even what were the steps to start healing. I hope it's not too late.