What happened?

I never thought I'd be thinking about suicide. I never thought I woudl be writing about how miserable I am. I never thought I could hurt this much.
What happened?
I have been thru some really difficult times, some really crappy experiences. So how was I able to get thru all that... alone? And now, here I am, I have friends and some family who love me and support me and who I know are there for me and care... and I can't get thru this one! I feel alone, altho I know inside I'm not. Why? Because I have finally opened up about my pain and my thoughts. 
What happened? I got weak, I let my walls down. When I was young I had a heart of stone! Nothing could break me- no matter how much I hurt. I went thru physical pain- that doesn't hurt like this. I went thru heartbreak in relationships- this is totally different level of heartbreak. I went to prison! My entire life taken away, my freedom taken away, my future, my family, my possessions... all gone. One would think that would push someone over the edge. No, that gave me more strength! But it also gave me a heart. As did having children. I softened. I started to care. That's what happened! I act strong, I say I dont' care... but it's an act... 
I can't keep up that role anymore, I had to let people see inside me or I was going to self destruct. And now, even tho I have allowed myself to be seen as the human that I am- I am still self destructing. With some help from the outside world, of course. This pain isn't just made up crap in my head- it's real, it's outside influences hurting me. People and situations that I have no control over... but they have gained control over me.
I let that happen. I allowed myself to be vulnerable. And now I pay the price.
This is not how I saw my life, or my death. This is not how I wanted things to be- ever.
As I said earlier, I have lost hope for any change, but I am still hanging on to each moment that makes me smile, to each thought that reminds me I can't leave. It hurts- I feel that continuing to exist is a responsibility at this point, not something I want. yes, I said exist- am not living anymore- I just exist.
What the hell happened to me?