I feel guilty each I remember the mistake I made

It was four years ago when I met this guy in a friend ’s party and we spent several hours of kissing before we parted. It was just a drunk night out with a friend .

Later on , I found out that he was the son of one of my father ’ s friends. My younger sister (20 years of age at the time) and him met and fell in love and became boyfriend /girlfriend .

Right after they started being together, I drove with him into town to meet a friend and I got pretty drunk . On the way back , he pulled in and started kissing me.

Nothing else happened , as we drove home and agreed to never tell anyone, since we were drunk and it 

didn ’t mean anything.

After a month, we were sitting together and talking and got drunk again. We ended up in bed together and did it again a week or so later. Later on, he tried to kiss me, but I pushed him away.

The problem now is that the thought of it is killing me. I love my sister more than anything else in this world.

If she would ever stop existing, I would too. I would die for her . And if I could, I would give my whole life to go back in time and undo it .

Their relationship lasted only a few months. I told her last year that we had kissed and she didn ’t get angry at me at all. I couldn ’t tell the whole story . I am scared deep within my soul that she will never forgive me or never trust me again .

I know that is the least I deserve, but I just can ’t . I will never be able to see myself as a good person again, but I need to do something, so I can function again. What should I do ?