Fe,
It sounds like you’re a fallback plan, option B, to this guy. He may be sincere, but even though the storybook dreams tell of men realizing what they lost and changing their ways… most of the time its not real. More likely is he is lonely, and so reaching out to you again… which will only last until a new shiny girl comes along. You deserve better than that. If you see and accept that, but still wish to pursue something with him in the hope it is the other way, the storybook way, go for it! Maybe that is how it is. What does your gut say? Mine says “i hope she drops him and move on”, but I’m not you, I’m not able to see all the information you have. It will either work out or not, and love is always a risk.
As far as the checking and obsessing, perhaps you’re lonely too? Much like we sometimes eat sweets when our heart feels empty, even when we know its not good for us. Consider spending a little more time self nurturing, such as metta practice? Its easier to make decisions in line with our heart when its full.
With warmth,
Matt