My stepbrother took me to his gym so I could join up, but we ended up having mind-blowing s*x at his flat instead. Our parents would be horrified. My mum was already divorced when she met his dad, who was also single. They fell in love and got married seven years ago.

I am 21 and her only daughter. My stepbrother is 29. He had already left home by then but he often visited so I saw a lot of him. I have always liked him and he was kind to me.

Then he got a girlfriend and we saw less of him. That relationship ended three years ago and he started to come round to our house more. I was moaning that I did not get enough exercise now that I have an office job so my stepbrother persuaded me to join the gym he goes to.

He arranged to take me there one Saturday afternoon last month. He introduced me to the manager and I took out a membership. It was all very friendly. My stepbrother then suggested going for a drink to celebrate and we spent the rest of the afternoon in the pub.

We both got very drunk and he said we should walk back to his flat for me to sober up before I went home. I made a move on him and he responded. We ended up having s*x and I stayed the night.

It was amazing and we seemed so close. The trouble is, he has avoided me since then. He is not replying to my messages and I do not know why. I have always struggled with self-confidence and now this has knocked me even more.

Should I confront him and ask why he is avoiding me or if he regrets what happened? I am scared of the answer though. I know our parents would be ashamed of us if they found out.

The other thing is that we used no protection and I am not on the Pill.