Talking with him won't do anything, he knows what he's got, and very soon the girls will know too. About all you can do is preach std safety.
Just because you and the father divorced should not mean father and son did too. My kids mom and I split 15 yrs ago but I still see the kids most every week, all school vacations, and all summer.
Large/medium/small I don't see much difference what its size has to do with you getting involved with it. Maybe just buy him a book on safe sex; I'm sure there must be many.
How do you know the size of your sons penis?
Looked at him in the crack of his door
did it make u wet
I think you had your toung in the crack of his ass.
cuz it went furter down my throat than his daddy did