Coparenting advice plz??

(Sorry so long) Hey everyone my name is Becca and I have a great son who is 8. Me and him left his father over a year ago due to mental and emotional abuse and honestly I am happy that I did. Well I got with a man who treats my son great, gets him almost everything he wants and everything he needs. He loves my son like his own. Well his dad is horrible to me and my boyfriend hates it. Like it has gotten so bad that my BD threatens my BF for no reason and calls him names and says he will beat him up, has said he will run away with my son and I will never see him again. He prays I will get in car wrecks and all these things then turns around and wants his way. Please keep in mind this is all because I don’t answer his million questions after I’ve already answered a million. He does have a house he just got with his gf and her kids and I fully respect her as long as she is good to my son we have no issues. Well he told me that he will never pay for his son unless the state makes him, so I went and got on child support. He fought it (go figure) and after 5 months he was court ordered to pay $419 a month starting in January of this year. He still hasn’t paid a dime. He asks me all the time to write it off and he will buy him things and I tell him absolutely not he needs to pay through the state website and he refuses. He is now $1,600 and some extra behind. I simply asked him today if he was paying child support today so I could get our son a computer to do his class work on and he ignored me and asked when he will be getting our son. During hit his virus he wants me to drive him almost an hour and a half away to bring him to his dad. Personally at this time hell no. Any other time he goes to his dad every other weekend. With zero problem until here lately because he expects me to call and make plans with him and he waits till about an hour before bed and calls to see when we’re coming. After a year we should have a half way mark but we don’t. Currently my ex is texting me about how I am a horrible person cuz I won’t let him see his son cuz of this virus and he is taking all the photos of me asking if he paid to court for full custody. You know I have never said that I wanted for custody until this very moment when I am so tired and so fed up with all of this fake crap. All I ever wanted was him to have every other weekend every other holiday including birthdays every Father’s Day and 30 days out of the summer for just him and because I asked if he was paying child support this morning so I can get my son a laptop for school he wants to go for full custody. Mind you this man has been in and out of mental institutions in the last year he has been in for I have photos of him rolling his weed and smoking it in front of our son I have photos of his switch and what I mean by switch is he can go from nice calm and cool and you completely pissed off. I don’t know what I can do to make this any better but everyone around me sees how crazy this whole thing is and I’m just trying to get a little bit of help from his dad and I will never get it. What do I do at this point? How can I make this stop? My son gets so upset cuz his dad doesn’t call him and he has to call his dad and just recently his dad started texting him but my son can’t read that well. His dad will yell at him and tell him he shouldn’t have to call my son all the time and makes my son upset. He will hang up on his dad cuz his dad starts shit with me and I ask him why did you do that and my son says “I don’t want him to make you cry.” This is so hard and I’m sick of this entire thing and my son is too. Now he feels like his dad would rather take care of his gfs kids rather than his own. At this point I’m stuck. Advice please??