I slept with my best friends partner and I think he'll find out
What was your reason for sleeping with your best friends partner?
I did it because I thought it would be fun.
Attraction can't be helped but sleeping with the partner of your best friend is wrong. It will your your best friend and ruin their relationship.
If I tell my best friend that I did it with his girl, it will be reciprocal. We both did something to each other.
You should never have relations with the best friend of your partner. This is something that can completely break your friendship as they may feel that they are no longer able to trust you.