I think, in his own way, your fiancé is basically trying to get the message across that he is not professionally qualified and therefore can't become your therapist for the rest of your life.
I guess that, if he had any childhood problems that he desperately wanted to share with you, he now can't do that because they'd be puny in comparison with the litany of horrible things you went through. So he just has to bottle all his troubles up and his coping mechanism is to try to get you to detach yourself from old traumas or at least stop bringing it up in conversation. (Your close friends might have the same problem getting their problems to measure up!)
If you were in the UK, you'd be able to get talking therapy on the National Health Service (NHS). It appears you have the misfortune to be living in a country that hates publicly-funded healthcare with a passion. Therapy is there but at a price - presumably beyond your means?
Is it one of the treatments specifically excluded from your health insurance plan? If problems stem from childhood but you start a health plan in your late teens/early 20s, do they weasel out of cover by counting it as a pre-existing condition?
However much your parents could have done with treatment for their problems before they raised kids, presumably they had the same problem of not being able to afford proper treatment or health plan restrictions. That's America for you.
So, your fiancé is wrong, in the sense that you really do need to get those traumas treated so that you can cope and move on with your life but he is right in the sense of that particular solution being as out of reach as a luxury car and that the only alternative is that you 'get over it', of your own accord.