Spree, though Miss Kelley may be a notorious liar as you state, she has attributed a direct quote to a specific person (Boy George's former sister-in-law) who is in a position to have known this.
The question, therefore, is the accuracy of the quote attributed to Bush's sister in law. If she does not disavow the direct quote attributed to her by Ms. Kelley, then its veracity would tend to be supported.
Bush has been widely reported to have been a chronic alcoholic and to have been a frequent cocaine user/abuser. Both habits, by the way, have been clinically demonstrated can contribute to impairment of mental functioning and cognition, as well as erratic and impulsive behavior behavior, balance problems, paranoia and deslusion in some cases.