My step son has a crush on me

On the night of my birthday I drank to much and ended up have sex with my stepson. I was pissed at his dad and not thinking to good I guess but really enjoyed the sex and only had orgasms like that one time before in my life and I had been slipped something and was fucked by 3 guys and at times all at once.
When I woke up the next morning I remember what had happen the night before and didn’t know what I was going to do as I looked at my young stepson beside me. He opened his eyes and pulled me to him sucking on my nipple and rubbing my clit. I told him to stop it that I needed a shower. I no sooner got in the shower and he joined me. Soon enough we were making love again in the shower.
I dried off after the shower and threw my robe on when the door bell rang. I went to see who was there and found a delivery guy with a box I his hands saying he was so sorry cause it was marked for delivery the day before. I took the box and opened it to fined and birthday wrapped box inside with a note saying “To the love of my life.” on it.
I knew who it was from, I opened it to fine and girt card for 6 full body massages at the spa I go to, plus a gorgeous diamond ring. I couldn’t help it the tears just ran down my face knowing what I had just done with his son. One thing I didn’t say last time was my husband wants us to have a child together and I stop taking the pill 4 months back and maybe pregnant with either one of them.
I orgasm very easy with my stepson but love my husband who is due home tomorrow afternoon. I wish I knew what to do, I could fuck the son when his father is at work or just come clean and cause a huge problem between father and son. Plus I think where we live what I did with the son could be rape of a minor.
I tried my best to say no to my young lover but by lunch time we were at it again. I cant see this having a happy ending, I hope am wrong.