I have never been so hurt

I found out my ex of 4 1/2 years, that has fathered both of my children (one boy, 3 in November, 26 weeks pregnant with little girl), has moved on after 3-4 months of us officially being over. My friend showed me a post that his new girlfriend wrote and they are expecting after being together for only 2 months...now they're moving in together. He never visits our son and is never here for us. He sends me money once every 2 weeks and that's all. He posts pictures of our son on social media saying how much he loves him when he never bothers to even ask about him. In the 4 years we were together he mentally, physically, and emotionally abused me. Also cheated on me more times than I can count and I still forgave him. We got engaged but yet again I found out he was cheating. Now to find out he had been talking to his new girlfriend for a year of us being together and now hes starting a family with her really hurts. Hes giving her everything he once promised me. I got in contact with her and warned her about how manipulative he is and how good he is at lying since I witnessed it all first hand. She doesnt care and is staying with him. I finally got the courage to press child support the other day, something I never wanted to do. I'm just super hurt and I've had depression most of my life so finding this news out while pregnant with his child doesnt help any...hes never been there for me but hes going to be there for her...I dont understand why I didnt deserve to have a family or someone to help me in my pregnancy. I just could really use some advice or tips on what to do..I dont want to feel the way I do anymore..

UPDATE:

I pressed child support a few days after this post and just last night I got a knock on my door. The SOB served me papers for joint custody of our son and our unborn daughter. Our son will be 3 on the 6th...there's no way he can go back and forth every other week and mess his schedule up. I'm already under so much stress being 28 weeks pregnant as of today now this on top of it..makes me worried I'll go into preterm labor and all that bad stuff. My ex lives in a house with 2 other roommates, where would both of our kids even go? He works 70 hours a week between 2 jobs....when would he even get time to spend with the kids and who would watch them? I refuse to let his new piece watch them. Hes never even bought a car seat in the time our son has been here...OH AND he didnt even get our sons birthday right on the papers he sent me...my exes parents are on my side and since I dont have a lot of money they're getting me an attorney and we're going to fight him in court. If his own family going against him doesnt show what kind of dad he is I dont know what will..