I'm really at risk of losing one of my closest friends and I could do with some help and advice.?

She most likely felt a little taken advantage of and maybe betrayed since you present yourself as a platonic friend. I also think it sounds like she is messing with your emotions! She may not be attracted to you ually and thinks that you make a great friend but that's about it. Sorry but male/female friendships (unless someone is gay) don't always work out because one of the parties will begin to feel more than friendship. Give her some time to sort out her feelings and maybe you should try to meet someone else in the meantime.