Diagnosing friends with personality disorders is the defining symptom of "Psych 101 Disorder." It's meaningless to insinuate she has a specific disorder, and you're probably wrong. It also makes you sound like a jerk for dumping a friend because they have a "disorder."
"Personality" means that behavior is stable across a wide range of time and social situations, which means even a very experienced PhD wouldn't diagnose someone with a personality disorder from looking at their behavior when they're severely depressed with new friends after a divorce. Depression, anxiety, and/or even a pill problem sound more likely to me.
You can just tell her it's very difficult to be around her and tell her specifically what she is doing.