Forgive me if I'm off-base with my response, but you remind me so much of myself that I have to share...
First of all, let me say that you have been incredibly candid and honest with the whole world about this painful situation. I also think that you have been very courageous with your feelings and with the way you have conducted yourself in your relationships.
Move Past Girl in the Glen
I also think that you should move past the "girl" in the glen to a woman who knows her mind, her heart, and is as smart and focused as you clearly are. That's what I did, and I have never looked back.
OK, what happened with me? Why should you care? I think the reason is because you're at a very vulnerable age. The early post-college years are tough. You're expected to make a splash, to have your head on straight, and to know what you want for the future. And, we think we do. To paraphrase Bob Dylan: I'm far younger now (at 35) than I was then.
I got married at 22 to a woman I'd had a three year relationship with. It all seemed so perfect, but it inevitably fell apart because as old and mature as we felt, we didn't count on the huge range of changes and growing that occurred during the next few years. We grew further and further apart, and didn't know how to come back together in a healthy way. In fact, we really married out of a desperate attempt to "save" the relationship.
Your desperation and desire for this "Girl in the Glen" are misguided. My guess is that you are hearkening back to a time when things seemed blissful, uncomplicated and easy. And, compared to college, the rest of your life will be complicated, boring, responsibility-laden, and too-often routine.
The solution is to seek new challenge and not look back.
I suggest you read what girl in the glen says about both you and her new boyfriend, Matt. You come across as a thing of the past. A wonderful love...but a former love. Matt may not be the THE ONE, but he's not far off either literally or figuratively.
I was also struck by the difference in tone between the two letters. You are clearly depressed, serious, committed, and clear in your devotion. She seems whimsical, casual, and kind of off-on-her-own.
Do yourself a favor. Let her go. You'll hurt, but you'll emerge from the pain more clear, happier, more self-reliant and ready for the next challenges in love and life.
Lose the girl...find the woman!!