I feel so bad,

Basically, as every girl has I have a group of guy friends as well as my close girl group, but like I know and always have known that I couldn’t go out/ fancy these guys cause they are not my type and also I’d feel weird about it especially being close friends with them all. But this guy is real close to one of my close friends and he tells her a lot and I think he fancies me cause she’s saying small things that she would never really say, and he’s being more nice to me than he ever has been. Last night he messaged me about class which I know is the simple way of getting to know someone. But I really don’t fancy him and couldn’t see myself with him at all, he’s such a sweet guy but not for me and he’s saying things which are really cringey. And I know I will probably get hate and saying I’m immature but I don’t know how to let him down cause I’m just speculating he likes me. But I need advice to tell him I don’t like him like that to stop him thinking I’m leading him on cause I don’t want to be mean