and said she's a right miserable girl In general.
This is very rude and offensive. How would you feel if your daughter heard this? She's a bully and although you know that don't let her think that she has any right to say things like that. Next time it could be in front of your daughter. It would probably do more damage to amend than taking the steps to stop that sort of talk now.
Approach her and tell her you will not allow her to talk about your daughter like that no matter how well meaning she thinks she is being. Don't focus on anything else other than that one comment she made, otherwise she will either twist the meaning of what she said or put the focus back on you and accuse you of being the problem.