I'd be creeped out too... and I was. Years ago this happened to me and I had to go loiter in another aisle while she chatted with my parents, who were too polite to tell her to go away. Yes they made "small talk" and were very annoyed that this person held them up. I'm not saying this is the same situation... but the attention from the ex was not wanted by myself or my parents. Some people don't get hints.
As for the mental health issue... I did feel that it was just tossed in there rather nonchalently and wondered why? Have to say I agree with Naomi's points.