Manipulative ex while I’m trying to move on

So I have a manipulative ex who’s messed up my life being with him for 6 years and 2 kids later, I stayed waaay longer than I should . Since I finally built the courage to up and leave him he has been constantly harassing me through text messages, blaming me for our family being broken and making accusations and believing his own lies .. I’ve recently been seeing someone and my ex found out because he questioned our 4 year old daughter so now I’m the bad one once again . I really enjoy seeing this man, he’s everything my ex wasn’t & treats me so good. But I’m having a hard time being happy when my ex is constantly draining me on a daily basis, going as far as threatening the guy I’m currently seeing and I don’t want to bring him drama all because of my baby daddy issues. I felt stuck being with him & I still feel stuck even though I walked away for the best. How do I deal with this bull crap, I can’t just block him out because he will blame me for keeping our kids from him even though he doesn’t come near them anyway.