My heart goes out to you.
It seems like yesterday that I went through something similar with my parents. They disowned me and my toddler son because I had left the org. When they did this, I told them that they are the ones who made the decision to turn their backs on me but that my love for them was too strong to do that to them, that if they ever changed their mind, my son and I would welcome them back.
I guess it was because of their love for their first grand child and the fact that they couldn't coerce me, that the shunning lasted all of 2 months. Of course, by that time I had gone into therapy to deal with the devastation. Later, I was disowned again. That lasted about a year.
The reason I am telling you this is because I want you to remember that what is said in the heat of the moment may not be what actually happens. Continue to be kind to your parents. If you do, you will never have the guilt of knowing that you treated them unlovingly. And who knows? This may just pass over in time. I hope that it does.
Congratulations on having such a wonderful fiance. His love and support will be needed in the weeks to come.