Loneliness

I'm consumed. No words can express the loneliness I feel in my heart. When once I was surrounded by those I love dearly and who I knew loved me now stands acquaintances and friends I am getting to know better. But there are those I miss so dearly that my heart just feels so defeated.
I don't get close to people very easily. When I feel like I'm getting too close to someone, I run away. That's just how I've always been. Nevertheless, I've always had at least one person that I knew I could rely on, someone I felt close to, that I could tell anything to. Unfortunately, I don't even feel like I have one person. I felt like I had one for a while, but that person has pushed me away and changed in a way that I don't even know who they are anymore. This makes me question myself and wonder if I even know who I myself am. Who am I?!
I feel so alone. I sit in large crowds most of the time, but feel so ignored and unnoticed. It shouldn't matter, I should be able to be enough for myself. I shouldn't need anyone else. Oh, but how I ache for a friend, a TRUE friend. I feel like I can trust nobody though. Not even myself.
I screw everything up. I ruin everything. I don't know how to change. I'm lost.
Who am I?