Dear Pastor,

I enjoy reading your column. I am 18 and having a problem. When I was 17, I got involved with my sister's boyfriend. It was not something we planned. I was living with my sister. Her boyfriend came to visit on his birthday. She and I cooked and got him a cake. She gave him a treat. We ate, had cake and wine, and took pictures.

Afterwards, he and my sister went into her room. I did the washing up. I suspected they went to have sex. My sister had to work so she got dressed and called a taxi. I asked if she had to go and she said yes. She said she could not call in sick. Her boyfriend looked sad when she left. He and I drank the rest of the wine. He said he didn't get any sex because she was on her period.

Something got into me. I was not myself. We started to play with each other. I knew when we went on the floor. I was conscious when he took off my bra and panties. We had sex. I couldn't help myself. We did it on the living room floor. I fell asleep. When I woke up, all the lights were still on. The television was also on and he was fast asleep. I had sex with my sister's boyfriend. When he woke up he apologised. I told him I was sorry too. We hoped he had not got me pregnant.

When my sister came home and asked me what time he left, I told her he left shortly after she did. My sister is very smart but she didn't have any suspicions. Since that time, I've stopped trusting him. They are planning to get married and my sister wants me to be her maid of honour but I find it so hard to look at this man.

What do you think I should do?

L.S.

Dear L.S.,

I know for sure you cannot tell your sister you had sex with her boyfriend. You have to keep it as a secret for the rest of your life. You did not give me his age but you were old enough to know it was likely you would get drunk after having so much wine. Alcohol breaks down one's inhibitions, and sometimes the things that one would not normally do when he/she is sober, they will do after they had alcohol.

Your sister trusted you. She didn't think that you would have sex with her boyfriend, so she left him there. That was a big mistake. This guy took advantage of the situation.

You are fortunate he did not get you pregnant. You apologised to each other. You will always remember what happened, but I repeat, you should not tell your sister about the incident and you should attend the wedding as maid of honour.

I hope you would be much more careful in what you do in the future.

Pastor