Sex with daughter-in - law

23 years ago i had a sexual affair with my daughter-in - law it lasted 3 year until she got pregnant we had great sex together but when she told me and the wife we was going to be grandparents it stopped i asked her is the baby mine or is it the sons she said she did not now and she said we will leave it that way i said ok when the baby was born it was a boy he now is a man of 20 and my wife keeps saying he looks more like me i say do he any way my daughter-in - law come to me 6 months a go and said she wants me to have sex with her again she said your son don't please me any more and you used to make me cum every time we had sex i said that was over 20 years ago and i said we can not do this and she said if you don't i will tell the family that he is your son and not your grandson i said his he my son she said yes she had the tests done i said you now it will break the family up and she said i do so i agreed to what she wanted and since then we have had sex many times when my wife as been out and she says i still make her cum now she wants me to leave my wife and her leave my son and move in together i said we can not do that lets jus go on as we are i want just lose my wife who i love but i will lose the kids and grandkids