Liking a best/closet friend but she is falling for someone else?

Basically, me and a friend of my have been extremely close for the past 4-5 years and only started liking her proper about a year ago. We would meet up do things together a lot our relationship was very solid but now I've been liking her for about a year now but I didn't know if she felt the same way and I didn't want to take any risks so I thought I would let it take time but now she has told me a story of how she was beginning to fall for another guy. She was mixed about it. I was abit broken by it but I tried to be as supportive as I can buy it did hurt me abit and the way our friendship is going I wouldn't want to end it on a bad note, what should I do?