I cheated on my husband with his best friend.
Why did you cheat on your husband?
I heard from my friends, that having extra-marital relationships is quite popular right now.
That is not a good thing to do. Stop cheating and tell your partner what you have done.
But I had so much fun with his best friend.
That does not matter. You have betrayed the trust of your husband by doing this. You need to come clean to him about what you have done.