AlwaysHiding it's good to hear from you, but I'm speechless about the behaviour of your DD's (ex, I hope) friends. Teenagers can be selfish, but that's on another level! As you say, new friends should be one of the goals for September.
Luckily, from memory, the experience of preparing for, sitting and receiving their GCSE results does tend to cause a period of fast change in teenagers, but everyone grows up at different rates, so friendships break apart and new, better ones form.
AlwaysHiding your DD has had so much to contend with, more than she should have had to, but the silver lining is that it will make her more mature and she'll find new friends who are similar.
Take care of yourself too. You've been through a lot to. 