I've done the distance thing - with a bad ending, but that isn't your question.

I've also been with someone who lived in the past - he said he was over her but kept talking about her to the point it got in the way of any relationship we could have.

Do the two have anything in common? Are you afraid that he will go back to her (or someone else) while you are in a distance relationship? He says you are his only one, how does he show that? From a distance it's easier. My problem was that when we got together with no plan on ending it (i.e. not for just the summer or a weekend) things started changing and I found out why he could only be in a distance relationship, and in a way it was a woman from his past.

I don't mean to discourage you, just warn you that things aren't always as they seem from a distance.