thanks Ladies for all the advice, it has been a long night.

Update
My dd come and jumped in bed with me early hours of the night (DF and dd were away for the night) and this morning we had a light hearted chat about what is really important about friends and how sometimes girls are blind sided by a boy etc. She seemed to understand where i was coming from and we agreed that her friend is actually a really nice girl and dd said she has never been like this before and she cant understand why she is lashing out at her. This girl is often at our place and has stayed over many times, i have her mobile number in my phone as she sometimes text's me mostly if dd's phone is flat or something. I mentioned to DD about me talking to her friend or her mum, she said no and really meant it by her face so i backed off as im happy she is able to talk to me and dont want that to change.
Ok then we got up and i was making breakfast while dd was in the shower when the phone rang, it was dds friends mother on the phone, she explained to me that her daughter was very upset and she couldnt get her to go to school because she was worried about an arguement she had with dd. Her mother was not aware of what the incident was about just that her daughter said im not going everyone is going to hate me now. I explained what i was told by dd and in know way do i think dd wasnt at fault either but there was no need for cyber and text bullying and she agreed. She asked to speak to dd but i said she was in shower and she said actually dont tell her i rang and at 8.30 can you make sure she answers the phone. 8.30 came around and i made myself scarce, the phone rang as planned and dd was talking when i entered room, she then left with phone to her room, about 10 mins later she came out and said her friend had apologised and was very upset by what she had done. Dd seemed happy but then on way to school she said mum i think that she is upset about something else and just took it out on me.
So this time it seems it might be ok but im still a bit weary of this girl, and yeah dd might be right there could be something else bothering her. Im proud of my dd for sticking by her friends but also worried that this will happen again. I had never seen her so upset.
Thankyou for your advice and for reading my rant