Lance your in the same situation, or similar situation, that I am in. I have been married for 15 years and even though I have done quite a few things wrong my current wife is also the same as you described. Very angry all the time and abrasive towards well, everyone and everything. That's the short summary of it.
I too am clearly flawed and I am admitting to my failures. The difference here is that I acknowledge my flaws where my wife will not, will never, or ever.
I think hearing your story has giving me hope because I have fallen into that trap of thinking I am the only one going through this, but hearing just a small portion of what you are experiencing makes me realize I am not.
I personally think after much research on the subject that while it stinks, its probably time.
Thank you and keep us informed.