Why are we here?

There was no actual way to show them how I felt. It's been too long and some words still hurt as much as they would a long time ago. And I hate it, I hate it that I'm so weak and that anything, just anything might hit me so hard. The smallest of all things will still make me feel like it's the biggest thing in the world. Like it's unsolvable and it'll last forever. They say "No, you're not like that. You don't know yourself, you don't know how much you can do." but how am I supposed to know? It's not something I've developed, at least I don't remember things like that. It's like I was born with a sense of what is right or wrong which is very peculiar. What I do is wrong, everything wrong that ever occurs to me, I'm the one to blame. Why? Why do I have to think like that? There's no reason. There's nothing that moves me to this belief, but I force myself. Every time things are doing fine, I find a way to show myself I'm gonna screw it up at any moment. Nothing bad happens, but I always expect them to come. The pain and the tears are always right behind me, waiting for a breakdown. But, again, what am I supposed to do? Who am I supposed to look for? I can't trust myself on that.
It's a curse, it's a stain that doesn't come out, no matter how hard I try to make it fade, it's always here. I try to let it go and I try to share all I keep inside like it's nothing, but I don't feel like doing that. How can I share something that has put me into so much trouble? And some are always gonna say "I've never seen you with any problem", well, no one has. But it's here, I guess. Not sure. Never sure. No. I don't know.