Should I forgive him? Should I give him another chance?

I've known the guy I've been seeing for over a decade, we had a long and heavy childhood romance that never quite faded, we have an extraordinary connection with each other, we've always said we're soulmates. I moved away when I was young and we drifted apart but never lost touch, we intermittently rekindled the flame every couple years but the timing was never right... til now. We decided we should give us a real shot and see what happens, so we started hanging out a lot over the last couple weeks, going on dates, talking, rekindling, reminiscing, cuddling, making out, staying the night with each other, all that. We aren't official yet, so there isn't any expectation of commitment just yet, but I just found out he's been seeing his ex over the last couple weeks too, and the thing is, just 2 nights ago I asked him if he was seeing anyone else and he said "no", so he lied. I asked him why he lied and he said it was because we had just started seeing each other and he didn't want to mess everything up, so I said, "what, you were afraid to lose me? or her?" and he said "both". So apparently he's not over her, but he's said we have something so precious and special that he didn't want to miss this opportunity with me, he said it was "time" for us to see where things could go with each other if we got serious finally. So he's got quite the history with both of us girls, except I've never slept with him, and our romance was never serious til now, whereas he was with his ex for a couple years, they broke up a year ago and she just started coming around again, all damsel-in-distress-like, at the same time he was pursuing me. He says he feels horrible, that he really cares about me, says he's not with her, and that he just didn't know what to do or expect because it was all new to him, but realizes he should have been honest with me. So should I give him another chance? Should I let him try to make it up to me?