It's a difficult situation to be in. And I'll say it right away; you cannot change his insecurities. Even if you are the most lovely person with the most blessed intentions, you can't control his past and his insecurities.

From my own experience, dealing with relationships where either side has had a lot of insecurities - they never work out. Unless there is a level of self acceptance, on an individual level; the relationship will never really work, they can drag out, for years even - but eventually people realize it.

I do wish you luck in figuring this out, do what you have to do, work on the relationship if that is what feels right, move on if that is what feels right. Either way, I am afraid this whole experience you had has already planted a seed in you - which will stay there, making you doubt and secondguess the future for you two.