Great to have you back mate!
Being cynical, and based on your previous posts about how she left, I'd be questioning whether she actually did sleep with someone as from all that you've posted on here it seemed like you were the only one who was ever fighting for this relationship. Telling someone on the other side of the world that you've slept with someone else is probably an easier conversation than just saying they didn't want to be with you as it would have the desired effect of stopping you in your tracks, which it did. If she told you she didn't want to be with you you'd probably still have gone over there and fought for a relationship that was probably long over. Got to be cruel to be kind etc.
Not sure if that scenario is any better than her actually sleeping with someone but the bottom line is that she evidentlly doesn't feel the same way as you did, so it is 100% the best thing as you could have moved your whole life over there for her and be left alone, with no friends or family in a vast new country!!
Rebuild, get an awesome job, get a swish new car, hit the gym, get ripped, get a fit new girlfriend and change your Facebook profile picture to you and her as no doubt your ex will be stalking your profile now!!