You said "i wouldn't cheat," so don't.
Option 1. Tell your boyfriend everything and be honest.
Option 2. Break it off with the other guy and tell him you have a bf.
Option 3. If you really want to see the other guy, tell your boyfriend you want to see other people.
Whatever you do, be honest about it.
If you've been thinking about breaking up with your boyfriend for a while and you've made a date with a new guy then it's definitely time to end your relationship, it's going nowhere.
And most importantly, no matter what you do, YOU ARE NOT A PEICE OF ****