Someone once asked...
Someone answered with kindness...
Follow what you think is right, not what other people and think is right. You can always back down. Feelings can change and you don't need to explain yourself if they change. Try to be nice to other people in general and take there feelings into account but you don't need to do something that feels wrong to you. If you are transparent with the guy you are no cheater or not loyal. You would be not honest if you continue something you don't want anymore. Good luck on your way! Don't be to hard with yourself!
Another soul answered...
It seems you have already made your decision. That's the hardest part. You just need to make peace with that now. Hard too, but not as much.