The 2 of you seem to have a very messy relationship and judging by the fact both of you have done some cheating, and I use some intentionally, you both seem to be settling for one another and internally searching for something you both are not finding in one another.
I'm sure the cheating didn't start with just the sex, I'm sure both of you emotionally cheated, flirted with others, crossed emotional lines with other people that people committed in a relationship don't cross, etc. Played it off as "that's just my friend we cool like that" when in reality you both want more than what your finding in each other.
I would in fact just move on. Decide if you want to be committed right now and if not, be honest with yourself about that and just date. If your going to commit then make sure it's with someone who kills your thirst to want to find something else. Make sure you feel whole with that person.