Is this cheating??

So I was in a relationship of 3 years... and I met his best friend we started making out and such and I use to sneak around to go spend time with the best friend. We never slept together due to the fact it would hurt the friend. But we both wanted it to happen... is that still cheating?? He was the only guy I looked at while in a relationship... so I finally left the boyfriend a few months ago so I could be with the best friend...