What about when the inner critic is right?

I've struggled with self-esteem since I was a child (I'm 21 now). That's pretty much, as far as I can tell, my parent's fault, to a great extent, in how they choose to raise me. My life, and who I am as a person hasn't helped either. Anyways, I really think I'm a horrible person most of the time, and I'm convinced that I just don't have the ability to do most things, or properly function, in the environment that people regularly do. Pretty sure I won't be able to live as an independent person.

What makes it worse though is that I can acknowledge my inner critic. I really can, and I know it very well, but I cannot rebuke it. Overall there's just nothing TO rebuke it with. Sure I mean I have a few things here which I'm not completely incompetent at, and I've seen from time to time my self-image increase a very tiny amount (going from nothing I like about myself to 2 things), but overall I just have no reason to like myself, nothing positive about myself, and no way to argue against the inner critic, which just makes me feel even more incompetent.

Everything in my life just goes to show that compared to everyone else around me I'm horrifically incompetent, and that really just brings me down. How can I argue against the inner critic when just about everything in my life points me towards the view that I'm worthless, unlovable, incompetent, etc. and have no redeeming qualities?