Backup/Please Help

This guy and I have been friends since 1st grade. 8’ll call him M. We are now 14. When we were little we had crushes on each other. In 7th grade, I liked someone but got rejected. Then I started liking M again. But then nothing happened. In 8th grade, I met a really nice guy and we dated for about a year. We broke up amicably seven months ago. I know that M liked me we I was dating this other guy because he sent me these long texts a couple times, saying to the effect of he liked me and I should be dating him. I think he still likes me.

I don’t know what to do. I don’t have feelings for him right now and if he confessed tomorrow, I would say no. But he’s my best friend and I don’t want to lose him. I also get this funny feeling when I think of saying no. I think, unconsciously, I’m keeping him as my backup. For a while, I always thought we would date and he’s a really nice guy. I feel funny about saying no, it will never happen”, because that’s so finals And then I feel awful because he’s so great and I’m a terrible person for stringing him along “just in case”. Yet I do feel like one day we could be good for each other, but I don’t want to start a relationship when I don’t have feelings for him yet. I know, I’m an awful person. But I have in the past gone back to liking him. But if I keep thinking like that, won’t I eventually trick myself into believing that I’m in love with him.

Please give me your thoughts or any advice. I know I’m young and high relationships don’t last. I know in 20 years, this will all be nothing. But right now it is something and his friendship is important to me.