Hello and thank you for writing to JustAsk!

I am sure that you are now experiencing many emotions in regard to your son and his recent (possible) sexual encounter which you witnessed.  

Communication always is key to a healthy family and trust within the family.  I would be inclined to reiterate any information you have shared (and perhaps add)  on safe sex practices, sexual exploration, and a parent's unconditional love and respect for their children.  This starter conversation may open the door for you to engage in other honest, albeit difficulty, conversations.

I also would offer for him to discuss male sexuality with another male, such as trusted relative, mentor, etc.

Thank you for asking this question. I am sure you may have asked something that others wanted to know, also.