Slept with my best friend son. Please suggest what to do??

I had committed a mistake. I am unable to decide what to do now. I am married women in my late 30's. Few days back i went to attend family function of my friend. She is my college friend. Once function was over she asked me to sleep in her son room since there were many guests and space was issue there. His son was already sleeping there on different bed. Her son is 19 yr old guy.I took a movable cot and slept. Late night i felt someone touching me. I was shocked to see it was his son. His hands were inside my top and he was touching me. I should had stopped him but i thought to see his curiosity. It was complete brain wash for me. He wanted me to remove my top which i did. He enjoyed it. Thereafter i asked him to return to his bed and sleep. But rather he insisted to see my bottom which i denied. He was insisting a lot for that, saying he has never seen it in actual. Later he removed my bottom. He was very curious to see women private part. When he saw and felt it, i asked him to go and sleep, he just started fingering me. I swept away with him and finally it ended with intercourse. I was very fool to agree to his demands. After that we slept. Early morning he came again and asked for another intercourse which i denied completely. When he insisted a lot i gave him handjob. He went to his bed after that. Then after sometime i left my friend house. She is my very good friend. I am feeling very guilty for whatever happened. Should i tell her or keep it secret. Our friendship will end once i tell her. She will blame me for all this. Please advice.

Let's put it this way...how would you feel if your own son or daughter slept with your girl friend / guy friend? And, would you like to know about it if it ever happened?

Technically legal. Technically an adult and it was a decision made by both parties. Otherwise it's rape. You consented, regardless of the build up that led to it. Therefore, you can't say you aren't guilty of freely participating. You either avoid if it is awkward for you. Or you ride the boat and see how far it sails.

First of all; "friends don't sleep with their friends 19 year old children, period". You weren't feeling guilty when you were participating. You as the adult in the situation had more changes to get up; put him in his place and leave his room. You are to blame, if YOU were ever her real friend, you need to tell your friend what happen, and understandably discontinue your relationship with this family. Yes you were both legally adults; so yes you can claim that, but that's not much to claim. ** Also Is Soulmate still advising at this site? Would love hear Soulmate perspective. Thanks.