really could use some advice

Okay ladies. 
So I had a still born in November. The father never came to the hospital didn't show up. Never saw his son. I did it by myself with my parents there. Fast forward to February. We have been on and off since our son passed because the father didn't want to be with me because he thought about our son. Well we decided to give it one last shot and we were good until we went out one night and he is drinking of course. He is an alcoholic but won't admit to it. He yells at me that I'm a slut for dating other guys while we weren't together. I end things with him. I get back with a previous guy I had been dating in janurary and he is honestly the best man I have ever known. He knows that there is a chance I might be pregnant with my ex again! He doesn't care. He is willing to step up and be a father. Out of a guilty conscious I tell my ex that I could possibly be pregnant and there is a possibility that it could be who I'm currently dating and not his but I'm not for sure. He blows up screen shots my messages and posts them on his Facebook with the title "some slut shaming for me ex" I'm petrified. Mordified. Humiliated. And he keeps tying to reach out to my family who I havnt even told yet and he has already sent the screenshots to my dad (so he said)  and tried reaching out to my brother. What would you do?