Carol is in good hands right now and that's a very positive thing. I just wanted to let you know that some of Carol's behavior could actually be attributed to the urinary tract infection (UTI). Did you know that it is not uncommon for seniors who have an UTI to experience psychotic episodes? These episodes typically produce the same kinds of bizarre behaviors that Carol exhibited; delusional thoughts, halucinations, agressive behavior, and extreme paranoia. No wonder you were at such a loss to explain these frightening changes in your wife! It is also reasonable to expect that Carol's frame of mind will improve dramatically once the antibiotic clears up any infection.
Hopefully this information helped a little to alleviate any misplaced guilt you might be feeling for somehow "setting Carol off!" You did exactly as you should have - and you couldn't have known about the UTI - in fact, seniors often have no symptoms at all - even with a serious UTI present.
If you can just hang in there, I think things are going to calm down again real soon. And I for one, admire you Bill for your good intentions. You should really cut yourself some slack though, and try to "give yourself the benefit of the doubt," as I'm sure you would do for anyone else in your position.
It might help to drop by a support group sometime and talk to other families going through some of these same things. I can only imagine how you must be feeling, but they'd actually know...