Hot stepmom extorted by stepson

I never imagined that I would find myself in such a predicament. My stepson found out about my cheating on my husband. And now he is b-mailing. He wanted something else. He wanted for me to strip, get on the bed, and pleasure myself in front of him. At first, I refused but then I realized he was serious about telling me if I didn't do what he wanted. So here we are, me on the bed using my fingers and toys to get off in front of my stepson. I can't believe that I am doing this. Hopefully, this is it, I do this one thing and we never speak of it again but I can't help but feel this is only the beginning...