Well... you could certainly give her a try. You know what the potential problems are. So you can be alert for them. Everyone (well... almost everyone) deserves a second chance. I don't know how involved your previous relationship with this person was. But this time around, just take it slow & see how it goes. Who knows? She might turn out to be a great friend. And great friends are hard to come by.

Of course, the other possibility is that she has her own mental health issues. If this is the case, things may not be better this time, even if she is sincere in wanting them to. But the only way you'll find out for sure is to give her a chance.