When to tell child about absent parent?

[lopsurn]

First time poster, desperate for some advice. Apologies in advance for the long post.
I had my DS(8) at age 17. It was an abusive relationship and a lot happened but being young and naive I stayed because I thought although I was being badly abused he didn't hurt DS and it was best to have a nuclear family.
My DP at the time had been through a lot of trauma in a short time and when I finally started to get the courage to leave another traumatic event would happen and I would be forced to stay.
At 18 I tried to leave and he attempted suicide. I was coerced into getting back together.
My logic of "well he hurts me but he's a good dad" was proven wrong. I was working away so he had care of DS, at the time we were living with family. When I got home and whilst feeding DS dinner the police arrived at the house after a member of the family had reported abuse to a doctor who in turn contacted social services. It turns out DP had (for what reason we still don't know) had bitten DS(at the time 8 months old) and left clear bite marks on his arm.
I was horrified and then ensued a long battle to prove my worthiness as a mother. DP denied doing it so an investigation followed, stupidly he had managed to convince not just myself but my whole family it wasn't him. It wasn't until we had teeth impressions done and matched to the bite mark did we finally have the proof he was the culprit. We went to court where he got a smack on the hand.
Fast forward to 8 years later, I have moved on and have built my life up. I have a great job and a great new partner. My DS is so amazing (although has had his struggles which we still battle with).
I had no contact with DS dad for 5 years until the DS paternal grandad (whom we have a fantastic relationship with) told me to claim for child maintenance. Me and Ex DP got back in touch through CM and after a wobble with him being floozy he started paying regularly.
I found out last year he's expecting a new baby and now this new baby is 6 months old.
My DS doesn't know about his dad because on my fault I blocked out the whole relationship and just wanted to ignore it all. But now he has a half sibling who I'm sure he would love to see or know about at some point in his life. But how do I tell him about his dad (he just thinks he doesn't have a dad, never really questioned it) and not only that but his dad has a child who he sees and has what seems like a normal relationship with. I don't want to cause any more trauma to my DS, his well being is my ONLY priority.
I have tried initiating a relationship with ExDP and DS after he hasn't seen him since his 2nd birthday but he just says he'll try then silence for another year. I've called social services who say due to the court order ExDP needs to be the one to apply to court for access. But what do I say to DS. Do I tell him about his dad and the new half sibling or just keep trotting on with our happy little life? Also he's messaged recently saying he's lost his job and new baby is a handful so can't pay CM, it's less about the money and more about the fact that his one and only commitment to his child is paying CM on time. I just don't know Adam from eve at this moment.

Do nothing until, as your son grows up and starts asking questions, then answer some truths without total harsh blunt reality.
He is better off not having a relationship with this man, it's a risk. You have this hope that now he is a caring father to his latest child, but read between the lines " he's a handful" could well mean he gets angry with them often and that's his excuse. I note it seems to be a "you'll get nothing as I lost my job" not a "payments will be much reduced as come out of my benefits ". He sounds like a waste of space so don't go getting fluffy ideas about him taking on a father role, because that won't happen. You won't be protecting or helping your son by forcing a connection with a potentially abusive person.

That has been my plan. Wait for him to ask and share the information necessary to satisfy his desires but also what is age appropriate.
I would like to point out that I would rather he had no contact for the rest of his life with his dad but I'm trying to be realistic and be prepared for every outcome possible.
I just want what is right by my DS and I'm so scared of this damaging him mentally when he's older. Every time his dad communicates with me (which is once in a blue moon) I make it clear that if he follows the court ordered steps and jumps through all the hoops then I won't be the one to stop contact happening - that is in the event a judge ever grants him that right. I would rather he didn't but I've extended an olive branch every time because he is telling people (and has said directly to me) that I am the reason he can't see his son.
Again if he just dipped out that would be easier but now my son has a half sibling in the world.

Only bring it up when he asks. If he wanted to know he would ask/fish for info. Its opening a can of worms, if he us not asking he may not feel prepared to open old wounds at this time, and once its out there he can't go back, leave that choice to him :)

Sounds like you have been amazing and its great he is doing well.

He can pay cms, even small amount of benefits till he is back in work, rubbish not to even put in any effort whatsoever. Wonder why he lost his job? Not the best timing with a baby.

Also i agree with you for him to jump through hoops via court..he bit a baby. I think most people would want a hell of a lot of reassurance to entrust their child near them again. His fault so he will have to prove himself like everyone else does and like you did back then.

I think that there’s a really good chance that he won’t cope with parenting his second child. So, if I was you I’d just wait and see what happens.

If he and his partner split up then you could get in touch with her and start a conversation about the siblings seeing each other occasionally.

Hi I had a baby with my ex , he left us when she was 3 months old for someone else ! Long story short , they had another child and he stopped seeing dd altogether when she was 5 . Dd is now 25 ! I have never told her about the other child because it has never seemed relevant. Her so called dad hasn’t made contact for 20 years. I hope you find a resolution to your situation.