You need to face a few truths about any of this before you move on.
1.) If she broke up with you for a muscular douchy guy, she didn't have much invested in your relationship. You mentioned it was a long distance or at least semi-long distance, I wouldn't be surprised if this was not her first tryst with another man, but she probably finally got the balls to break it off with you.
2.) You needn't cut yourself off from anyone but her. I read the response about replacing one pain with the pain of solitude, but all that would really do is prevent yourself from moving on. One night stands can be fun, but there is no reason that a one night stand with someone you really really like and are attracted to can't turn into a relationship with that person. I met my current girlfriend of over a year from an ad on craigslist (you must look in the strictly platonic section). We met up, we clicked, and it became a lot more, she is possibly the best girl I have ever been with even, and she tells me that I am the best thing that ever happened to her. But, from going through what you have gone through, I can safely say that you need to stop talking to her. I know it seems mean, but if she is still contacting you it's because you are an emotional crutch for her, but she is just using you if she doesn't reciprocate your feelings. You are most likely fulfilling an emotional hole that the big muscular douchy guy isn't/can't.
3.) Spend time with friends when you need to, but don't be afraid to spend time by yourself, either occupying yourself or even with self reflection. Those are the toughest times, but also the most cathartic. There is most likely emotions you need to get out and it will help you to experience them (Dane Cook had an extremely funny little skit about guys needing to cry, I laughed so hard I cried... Which brings me to my next point).
4.) Laughter is your best friend. You will be able to deal with quite a lot if you have some really great times that you can laugh at. When I went through an extremely emotional breakup, I would drown myself in funny things (movies, stand up comedy, reminiscing about funny things in my past with friends). These also may be the only time you can escape thoughts of her or your situation with her.
5.) She doesn't care about you. That is going to be the hardest thing to face. Sure, she will say she still loves you, just not the same, and similar things. And she may even believe them, but she ultimately doesn't. She cares only about herself in this situation. So you should try a little selfishness for yourself. If she calls, don't call her back. If she emails, don't email her back. If she posts something on facebook, don't respond. And if you do, make the response completely platonic and betray no anger or emotional hurt to her. Believe it or not, the hardest thing she will face is the idea that you have moved on from her, especially after all you have been through with her, and if your smart, you will move on.
These are just some of the things I learned from breakups with women. They do this really weird thing where they want to let you down easy, so they try to be friends with you as if they are doing you a favor, but they aren't doing you any favor, they are simply stringing you along. They don't mean to do it (most of the time, I'm quite sure), and they think they are helping you out, but they aren't. Good luck.