Hi and thanks for getting in touch with me.
It sounds like you have been having a really bad time with this person and her twin. Ganging up on you, taking money and embarrassing you is not acceptable behaviour. Saying you are a horrible best friend and feeling scared of them in lots of different ways, sounds to me as though they really do bully you.
There is lots of advice and information on the ChildLine website about how to deal with bullies and being bullied. So maybe you could have a look at that first of all.
Have you thought about anyone you could talk to about these girls? Does anyone else know what's happening and how bad you feel about it? You should really try and speak to a teacher in school.
Talking about it can sometimes be a really big help and it might help you to come up with some ideas of what to do. I don't think that you should have to move schools why should you? You've done nothing wrong. It would also probably be quite hard to sort out.
If you look at our ChildLine message boards and other Ask Sam letters you might be able to see what other young people have done in similar situations.
Don't forget you can always speak to one of our counsellors on the phone 0800 1111 or online in 1-2-1 at any time.
I hope this helps
Sam