Open Question: Help please. Child involved, Any advice on how I can get over my ex. 3 years of cheating and lies.?

We have one child, 7 months later, he left. This is 2.5 years ago. I think he is a downturn, but the fact that he was having an affair, and I'm pregnant, and I was a newborn baby at home, he would leave her in the weekend travel, and so he married her recently, she has three children. I hope I can get over it, but I told him so angry, we have our son the same time, I hated it. I did not convey anything to me, he would take him out of the city over the weekend, not even telling me. I know what to do, I do not want to be painful, I have to move on, I want happiness, anger keep coming back, I do not want to hate him.