Yes, that’s what I meant- court order in place. I also like to get some advice, different views- I just try to help but of course you are free to feel that my view is wrong. That’s fine.
I think that this needs a legal route. Document everything, act in the best interest of your sons, try to promote the relationship with the other parent but emphasise your concerns about the dad- as if you were a social worker.
You don’t know what the dad is saying to the older son (negative things about you, etc.). It’s important that you have a contact with your son. It’s important that both siblings have a bond/contact too. The dad cannot alienate you and damage mother/son or brother/brother bonds.
Always in the best interests of a child – this is the court’s view. You should have a contact with both children. The dad should have contact too, assuming that he is ordered to behave safely and it is in the best interests of a child and it doesn’t damage anyone’s relationship.
All the best to you and your children.