Should I Stay or Leave? Is what he doing considered cheating?

I have been dating this guy for a little over six months, I have known him for almost two. We started dating in March and by June, July issues started to arise. I confessed a month into the relationship that I had slept with my ex of almost three years, almost a month before agreeing to officially be his girlfriend. I know it upset him so I was over accommodating and loving. I went online with my computer one day after he left for the evening to check my myspace only to see he never logged off of his. I find that he has been messaging several females flirting with them, telling them how beautiful they looked, trying to make arrangements to get together. I was taken aback, to say the least. I did not yell or scream when I confronted him, I expressed how hurt I was and he become defensive even throwing in the fact that I slept with my ex before we started dating. We talked and I thought all was resolved, and then again I come across more myspace messages and text on his blackberry with him doing everything over again. The first wound hadnt even healed before he was back at in 1 week. I still stayed by his side, the third time I caught him doing it again and to make it worse he was deleting things so I couldnt see how far he took it. I ended it and we had a "family" gathering where every1 sat and listened to us each and then helped us resolve things so I continued to move further with the relationship. We used to spend everyday and just about every second together but I recently relocated 30mins away and now only see him once on the weekday and then our time together is the weekend. I have once again noticed that he may again be starting up his old pattern, and I love him more than anything, he takes note and even informs me I do too much for him. If its true and I do too much, am very loving, and faithful then why should he behave this way and because of his behavior should I continue to be forgiving and stay or move on? I am very confused he is loving but i dont think that should excuse his behavior nor should it give him the right to appear unfaithful.