Dilema

I am a married guy with a family.
I say I am bi sexual as all my porn is gay and I play on a gay chat site. I have never had sex with a man, other than cyber sex...in great detail.
Last weekend I was playing on my usual gay site and a guy came on with a pic. No face but a full body shot with a large erection. A stunning body.
Just above his penis was a scar. I have known that scar for 10 years.
I hit on the guy...I was posing as a early 50's gay guy.
I felt really bad but couldn't stop.
We did a role play. A Step father son situation. The scene was driven by him.
It was graphic...we had heavily detailed sex...we both ejaculated, or I did and he said he did.
In my mind I knew who I was fucking and it turned me on like nothing ever has before.
He kept saying fuck me. Fuck me. And I kept fucking.
I have never even thought our son could be gay. He is "too busy studying" to have a girlfriend.
He is very good looking in a masculine way.
My dilemma is. ONE do I somehow get into a discussion which could lead to him outing himself? TWO I would really like to have sex with him. Hot passionate sex.
I have started masturbating thinking about him. I get an erection when I see him and have to excuse myself.
I feel sick about this. How sick am I? What the fuck do I do? I am erect and very wet writing this. I will ejaculate as soon as I post.