You met a woman and she was great while you were dating and seeing each other a few times a week. You moved in together and got to know her better. Then you found out that the person you though she was is in fact an act she put on (consciously or not) during the early honeymoon period. Now you've got to know her better, you know what she's really like deep down, not just the superficial mask everyone puts on for the rest of the world.
It seems like you are stuck because you remember what she was like to begin with. You want the return of all those feelings and that happiness you had at the beginning. But that's not who she really is. That was the personality she put on to make you happy in the early days. That was the person who got you engaged and nearly down as the owner on half your house. The person who nearly married you.
I think you've got to realise that's not who she is. The person you know now, the one who stresses you out, is who she really is. If you'd known her that way at the beginning, would you have even got past a few dates? You're romanticising her as the woman you put on a pedestal at the beginning of the relationship (which a lot of men do), and you need to decide what you want based on who you now know her to be, not how you want her to be. That fantasy woman isn't inside you're fiancée, it's only in your head.
Thank you sir , you have hit the nail on the head with me and my recent ex