Welcome and be welcomed to the non-lurker side of the wall! As you know, ADISC is a wonderful place and is unique in that near everyone here is wearing a diaper.
Well, you should have told her before you asked her to marry you as there has to be some level of honesty for your relationship to be long lasting. There are several Thread that deal with tell one's SO.
Understand, she maybe shocked and it could all go very wrong.
Be very honest with yourself and her!