How did Diane know how well she knew Will, even if she'd worked there only a week. And then you go on to project personality traits onto her as to her motives. And even if she was over emotional, it's possibly a one-time deal. If somehow she repeats that sort of thing talk to her and give her notice. Don't act harsh based on pet peeves and jumping to conclusions and possibly overgeneralizing as to peoples personalities. It's fun to act harsh based on pet peeves, but it reflects poorly on her personality.