Dude, all I can say is that my heart goes out to you. I'm just glad I'm not the only one posting threads about how love life can really take a hold of you!
But seriously man, I totally can relate with you. When you've spent YEARS really only knowing ONE person, it's devastating (to say the least) when you lose that person. Although you haven't COMPLETELY lost that person yet, you are anticipating it and trying to prepare yourself for a HUGE life change. I've only read about 3 pages into the thread, but so far it sounds like you guys are being respectful to one another, and that's a great thing. If you guys a TRULY best friends, then this is a great thing for the both of you. I know this is going to sound really cliche, but this is a blessing in disguise. Your partner is going of to "grow" and experience the world, and this is the perfect chance for you to do the same! Find yourself, be productive, become successful. BE SOMEBODY! I totally know what it's like when you're with someone for so long, you just forget who you are! It's like you can't function without the other person.....
So, to be blatantly honest with you, this is going to be a very difficult time in your life (if it isn't already). Just buckle up, BUT MOST IMPORTANT,
KNOW that things
WILL get better. They
WILL. One way or another, things will slowly but surely get better and you will look back and be happy again.
Just to give you an idea (if you didn't know already) I broke up with my GF of 4 years in February. As I posted here, I was going to propose to her and she was supposed to move out to LA with me this coming August. To sum it up for you, the topic of me possibly wanting to live out here came up and she didn't want to. I was upset, and she "suddenly" decided that she didn't want us anymore...... I spent months rattling my brain wondering how my "best friend" could just leave me high and dry, especially after all the plans we had. And how much I was sacrificing for her (starting selling off my collection). Well, when I returned home in May to confront her I discovered that she had been partying it up, making out with guys and had already jumped into another serious relationship with another guy. And to put salt on the wound, she just rubbed in my face how much better the new guy was and that I was just a terrible BF the entire time...... So YA. Be grateful that you're not in THAT situation!
Anyhow man, if you're curious to read about my story here's the link:
https://www.sideshowcollectors.com/forums/showthread.php?t=71550
Anyhow, best of luck to you man. So far it sounds like it's the initial shock (and trust me, I know it hurts). But it sounds to me that you have LOTS more to be grateful for, and that you have a pretty genuine relationship with each other (since she respects you). So just hang in there man. And feel free to contact me if you need to chat!