Single moms help?

Michelle • Ryland born 11-13-15💙
I am 24 weeks and 2 days pregnant with my first, a baby boy I couldn't love more if I tried. My sons father and I broke up when I was 6 weeks pregnant due to relationship issues, I later found out he was doing drugs our entire relationship and cheating on me with several other girls. He got himself cleaned up, and I told him if he screwed up again, he would loose all rights to his son. He already doesn't see his other 2 boys from his ex wife because of drug use. I told him I won't allow my son to be raised around that and if he wants to be a dad, he needs to get it together. 
He got a job, moved into clean and sober living, and had 3 months clean. I thought he was doing good. He even said he was putting money aside for our son. 
Today I got a phone call from a mutual friend of ours that my sons father is using again and got kicked out of the clean and sober living. He has a new gf who I am pretty sure is using drugs as well. I have lost all respect and compassion for him. And he has lost all rights to my son. I will not put his name on the birth certificate. I will not allow my son to be raised around someone who is on drugs and violent and mean. I love my son too much. 
I need advice and support asap. I am completely lost. I am now coming to terms with the fact that I am going to be doing this on my own. I have an amazing family and the best of friends who will also be there for us. But as angry and heartbroken as I am knowing my son won't have his dad, I am also grieving this relationship that has been over since March. I was in love with his dad. We were engaged and planning to move in together. And now my image of my family is nothing like I planned. HELP?