How to end a friendship

About 3 years a go i met this dude at school who was suppost to be just a classmate, however i used to help him in some school stuff when he need as well as that we went through some situations which made him think that we are freinds. Maybe thats my fault cuz i am alwyas kind with others and make them feel that i like to have them around however for me he was just a classmate nothing more and to be honest (i dont want to sound rude) but i never enjoyed hangging around with him. he also became part of our group, i believe my freinds got along with him but i never. what makes it worse is that he likes me the most between our group and i believe he sees me as his best friend. I know thats sad but i cant force my self to like someone who i dont feel comfortable around. he alywas would ask me to go out or have lunch together and i always force my self to join him, however recently i would make excuses to avoid going out with him. i tried to ignore him alot but somehow he never get it. what makes it worse is that we live really close and he is already part of our group so i can’t even tell him that we should end this freindship

So was it my fault from the begining ?, and how should i deal with this?