When and how do I tell my kid the truth about his dad

My eldest son’s has never asked why I’m not with his dad. But I over heard his friend ask “why” he’s got two dads, he responded the he doesn’t know. I know one day I’ll have to tell the truth but how? I don’t want to hurt or confuse him, I don’t want to break his trust and regardless of all his father has done to me - facts are facts but I don’t want to come across like I’m throwing his father under the busI left his dad when my son was roughly 7months old. The relationship started when I was 17 ended when I was 21. He was highly abusive and I didn’t know how to get out (he controlled me, isolated me, had guns pointed at me, destroyed my belongings, attacked my workmates, verbal, emotional, physical abuse - I was hospitalised multiple times, fractures, breaks, concussions,stitches and more) he went to jail for one of the attacks, he got wind I was trying to leave and got me while I was walking home from work. I kind member of the public called the cops. Between that event and before he had court I fell pregnant.He made a big act to tick all the boxes to get help, he was released less than a month before the birth. At the birth he let it show he hadn’t changed, just spun out at the doctors and midwifes. There were a number of complications which meant I had to go into theatre, he didn’t come. My son was not well so We stayed in hospital for over 3 weeks after. He came and went. And once we were able to come home I found out the job he had been going to didn’t exist and was just an excuse to not be around. The abuse started again.Son still unwell and had two surgeries before 3months old.Flash forward roughly 7months, I’m doing all the parenting while he’s just bumming around. One night I get my son to bed, make myself something to eat and the father starts yelling at me to come to him. I came but not as promptly as he wished. He attempted to stab me with a pair of scissors, I avoided it. He went to the kitchen to get a knife, I board myself in the room with my son and call the cops. Cops arrive and he takes off.This was the end. I was done. Police helped me organise full custody of my son and a protection order the next day. They found the father arrested him, pressed charges. I finally admit to my parents the truth and they take us in open arms. I said the father could have the house, the police organised for him to not be there while I pick up my stuff (I let him have everything, a houseful which was all brought by money I earned, all I took was my clothes, my sons crib, toys and clothes)He turned up while I was collecting and started smashing everything before attacking me. Tackling me pinning me down and strangling me. My mum has to try remove him off me while getting hurt during all this. He takes off. Cops come again. Sent me to hospital. Another charge added for his court date.today My son is 9, healthy and wonderful. He knows his father and that side of his family. I am married to a wonderful man who my son calls dad and we have another son too. The two boys are best mates. via /r/Parenting https://ift.tt/36QjPjz