Hey Sweep,
Having gone through the mental anguish myself, let me tell you.
1. Life is toooo short to be miserable and try to ponder what went wrong. Just go ahead and move on.
2. At least there isn't a child involved in this... or is there??!!
3. Always look for the silver lining in this cloud... All the money you would've spent on her, you now can spend on yourself.
4. You have time for yourself... Ever get annoyed when they say something like, "you used to...?" ie. you used to tell me that you love me, hug/hold/kiss me..."
Anyways, it seems a little wierd to begin with, but you'll be amazed at the freedom you now have. Enjoy it.
Oh yeah, BTW, another thing to remember is that because you two weren't married, she can't screw you on "your" stuff. My ex left me with the clothes on my back, and my acoustic guitar.