Aliaslux... I'm pretty new here too. Just a couple of quick thoughts... I'm browsing all over here to get some ideas about my situation too.

Your fiancee may not have really come to terms with his past, and may be in a pattern where he's always repeating his past actions because he doesn't realize or understand he needs to approach the problems in a different way.It's hard to solve problems using the same thinking pattern that was there to start the problems.

Second, if you are at all unsure of anything, then perhaps your intuition might telling you something. This time/situation might not be right for you... you might not be ready or able to tackle a marriage yet. Doesn't mean you'll never be together or that you won't be married, but the stress of his life will affect you too. It's hard, and you could become his emotional sponge and you might end up being resentful.