Guys, I'm not sure what to do...

I just got left by my girlfriend of almost 2 years. I had devoted myself to the relationship, and our mutual happiness. I learned so much about myself, and about her, and i thought we were on the right track. I was easily within the "Pop the question" time frame. Obviously she wasn't. She gave me a few reasons like "I need time and space to figure out who I am and who I'm becoming." & "I feel like i've lost myself in this relationship." I thought I always celebrated the things that made her unique, and now, I'm alone. After this long and this much dedication, I realize that I wanted no one but her for the rest of my life, and also that I can't really function without her. Lingering thoughts about the quickest, least painful, and least messy ways to finish myself off grow more and more present. I just had to tell someone.