Your new guys sounds like a keeper. I'm glad you found someone decent that makes you happy. If I look back on past relationships I have lots of what-was-I-thinking? moments, I'm sure we all do! I guess we have to kiss a few frogs before we find our prince.
Friendship is always a good base for a...
You guys were together for a long time, so that means he must care about you. I think you should send him a text or email and tell him you thought about what he said, you realise he was right, you were a bit too insecure blah blah. Tell him you miss him and you'd like to see him if he had time...