The Kazon mothership would have destroyed Voyager
had Chakotay not taken action, with no weapons array or backup close by they were out of options.
Janeway pleaded with the Caretaker to send them home, though knowing what was coming and the damage it caused first time they could have reinforced the ship for the journey home and ensured the crews were kept safe.
It was her decision to destroy the Array (with weapons that were magically back online), but it would have been destroyed even without the Kazon collision. Taking the action she did was a huge violation of the Prime Directive, but when weighing up the lives of 150-ish with thousands (if not millions) she could have been said to have done the most compassionate thing.
trapped in the DQ is no one's fault, but rather a random convergence of incidents that had only a finite number of outcomes, none of which were exactly very favourable.
I get why she blames herself at times though, as it is something that she could feel guilty about, even though she did it for good reasons.