My best friend only wants to be friends

Basically we had an argument and has said after time to think she only wants to be friends. She always said she loved me the same amount as her mum and sister and even told them that and that she saw me as a sister. She always said that we were going to go travelling together and get a place. I don’t get how she could just throw me down to a friend as I could never do that to her as I love her way too much.
All in all it’s final she won’t change her mind and I am about to start sixth form on my own. She was my only friend no one else would talk to me and a lot of them people who would talk to her are going there too as it is the same school as our secondary.
I just need some advice on how to cope with this as she was my world and now it’s all come crashing down. I also am not very good at making friends so any advice on that would also be greatly appreciated.

Thanks in advance x

It's sad that things aren't well between you and your best friend. However, you can't restrict your whole life to having one friend. It's time to start to widen your social circle. Starting sixth form could be a good point to start with. It is still possible to make new friends, and it may be that new students from other schools may join. Try to talk more to new classmates and look to joining more activities and clubs. You could also look to meeting people outside of sixth form, for example, volunteering or local clubs.

You can't be dependant on having one friend, i'd rather have no friends than one fake friend who is toxic