I'm very sorry for your pain and the loss. I know it feels devastating now, but believe me, over time, it will get easier and better for you. It will take time though, and you will grieve and mourn the loss. But that doesn't mean that all hope is lost for you. She is not the only one in the world for you - I know it may feel that way now, and I understand the feeling as I am going through a similar loss with my ex fiance, but there are others out there who will understand you, too.

And a word of caution here, too. Getting involved with someone who is already in a committed relationship is never a good idea and typically ends in pain and suffering, as you are experiencing. As someone else said, she has cheated on her fiance and therefore, cannot be fully trusted. I also agree that she does not have to marry him. She is choosing to marry him, and that's her choice, which will most likely, will not be a happy marriage for her. If I were her, I would walk away. This is not a match made in heaven.

So learn a lesson from the pain... this is an opportunity to grow from the experience. Next time, make sure the person is single and available. Lessons the chances for hurt later down the road. (((((((sending big hugs)))))))))