Here's my view, only because you asked for opinions.
These guys are steering in the right direction by telling you to be upbeat. If a woman sees you down over her, she will eat you alive. You will have no chance of getting back together with her at all because she knows that you will be around whenever she wants you to be. Trust me, you will become "that guy" faster then you can belch after a protein shake.
You MUST! act like you are TOTALLY FINE WITH HER DECISION. That does not mean be an a$$hole to her and blow her off. That means that you know there is nothing wrong with yourself and that she made this decision for her own selfish reasons and that doesn't reflect on you as a person.
As far as getting back with her...Well, if she gives you a damn good reason for the break up and, then apologizes for everything AND assures you it will not happen again...go for it. If not, you don't want to go there. You think it hurts now with just the pain of not knowing why? How bad is it gonna hurt when you beg her back and she just pulls the same shit again or decides that she is unhappy and cheats or something like that? Not only will you be hurt but you will feel demoralized and stupid, "I should have ditched this chick a long time ago and I wouldn't be hurting anymore!"
Second chances are almost never worth the effort. It usually winds up being a crutch just long enough to find someone else. Hardly what you are looking for...
If I was the voice of reason for you I would be saying, "suck it up, as hard as it may be now, and let her go." You will be much happier in the long run. And a final note...Women like men who are strong and decisive. I have seen many more women return to a man down the road, after he has just let them go without issue, then I have to a man who pleaded for them to stay. Be strong! Be decisive! and Be yourself!
Hope this helps?? I am always willing to take time for a brother in need.