Forgive me, and whilst I feel sorry for how you're feeling, but if this other woman is very happy in Canada with her new man and family (kids involved?) then is it not a tad selfish to play the guilt card to get her to come back?
I'm sure I don't have the full story, and if you'd like to PM instead of post here that's cool, but that's the first thing that came to my head. You're only 23, a year younger than I was before my fiancée left me for another bloke and I thought I'd never find someone else, but I did and now I'm married to that person and am happier than ever.