My DD and her DD became friends at nursery and subsequently we became very good friends because of this. Her DD is an only child that struggled to make friends and was taken under the wing by my DD. My DD has helped her over the years with her anxiety, particularly at parties etc.
I got the feeling that over the past year my friends feelings towards my DD has changed. She would often make digs at my DD and make out like it was a joke.
The girls have just started reception and my DD is having trouble her friend being unkind to her I.e hitting her, excluded her from games etc. On the first day of term, after a 6 week break from each other in the summer, my friend made a big thing about her DD meeting up with my DD and going in together and meeting up at the school gates prior to going into class as her DD cries every morning.
I gently approached the hitting issue with my friend and was shocked and surprised to learn that when the girls were at nursery, my friend had made a complaint to the nursery about my DD. She said my DD was nasty to her DD and it was not a healthy relationship. She asked to change her DD's nursery days and did so, lying to and telling me it was because of work.
I approached The nursery and asked them what the issue was with my DD and why was I never informed of her behaviour to which they replied saying they had no issue with my DD and in their opinion it would be in my DD's best interests to find a new friend. I threw approached the school to check that they hadn't noticed anything going on and again they said that there was no issue with my DD's behaviour. I then tried to speak to my friend to find out exactly what her problem is with my DD and she completely went off on one and stormed off saying that my DD is not healthy for her DD.
I've been into school today to find that my "friend" has been to see the headteacher and requested that my DD be kept away from my DD.
I'm so confused as to why my friend encouraged her DD to meet up with my DD at the start of school and effectively make her dependant on my DD when she clearly has such a strong dislike for my DD 
The friendship is over between me and her as far as I'm concerned as she's lied to me and the way in which she has treated my DD is not on at all in my opinion but how do I deal with this from now? I haven't slept in days for thinking about it trying to make sense of it. WWYD?