People want what they can't have ...shogunblade said:snip
The question remains of why you want her back. The point is you don't love her ... what a foolish concept. You broke up, and then you feel slighted now that she's happy and you're not. That's not romantic love ... not affection for one's friends or camaraderie amongst a tight knit group of peers and colleagues. So you're kinda not fooling anybody by the whole 'nice guy' routine. Everybody says that, and to your benefit 90% of Humanity also shares this common affliction for the need for approval.
I mean c'mon ... you broke up, she's now married, and you're slighted. Then you tell us you're a 'good guy' despite no ability to actually validate this. All these paint the picture of someone obsessed with approval, and it would make sense you feel the way you do due to it.
As I said, 90% of Humanity attaches itself to self-esteem like a toddler with it's safety blanket so you're not exactly alone. Everybody feels the same pangs (albeit to al esser extent) when we see our ex-lovers and former significant others with other people.
Ultimately your salvation is in much the same way achieved as others have achieved it ... by getting over it. There's no 'deep' and transcendental answer out there for you other than the very simple 'get over it'. What else is there? What advice can be given?
Ultimately if you respond this way with your ex you'll probably do it again with the next lover you have so I suppose learning how to get over this will prepare you for that as well.