DS is 6 (just). His bio father has never been interested, wanted me to have an abortion, avoided paying maintenance for years etc. He does pay now, and occasionally we text, but it's always about money and he never asks about DS.
DS has, however, seen his paternal grandparents, auntie, auntie's boyfriend etc pretty much every week since birth.
I met DP when DS was 1, and got pregnant with our DD very quickly. DS has my surname, bio father is not on the birth certificate and he thinks DP is his dad.
It breaks my heart to know that we will have to tell him at some point that DP is not his dad. When and how would be the best way to do this? And what if he wants to see his bio father? Bio father would probably agree - though is very unreliable - and I know it's very selfish but I would hate seeing our family split up like that.
Does anyone have any advice?