Should I tell my Son?

My son is 12 years old and lives with the man he knows as his father, when we were divorced the judge asked me if i knew where the biological father was and since i didn't they granted my ex as the father and changed his last name to his. Now over the years little things have come out on his 4th b-day the man he knows as his father told him that he wasn't his father and so my son when he came home asked me about it and I told him the truth and told him that if he wanted me to I would find hid real daddy and he said yes. So it took me 7 years to find him which i did and told him about his son he thought i wanted money and i haven't heard from him since. In the last year my ex's mother has told my daughter who told our oldest son but not to the son thats not his. My son has made hints as to wanting to know when he can decide where he wants to live. My ex has said he will do whatever it takes for him not to find out the truth I feel that its time to tell him I have never lied to my children and he hasn't come right out and asked since he was four. So i guess my question would be would it be a good time to tell him or not he has already asked why his last name was different from the others and why he doesn't look like them. My ex was very abusive to me and disiplines the children to fear him which i don't agree with. So any thoughts would be great I am just stuck on when is a good time to tell him.

[91004]

What is it exactly that you are wanting to tell your son. Doesnt he already know that your ex isnt his dad. You should have been honest from the start and not let him think the ex was his dad.