What should I do as a boy loved me madly and is waiting for me knowing that I have no feelings for him?

I've been there and this is what i did: i had a boyfriend. when he left for a year,this guy I've known since i was little admitted he loved. i was shock, horrified, and flattered. i loved a little; but even then not in the same way. so i did one thing: i got to know him, and we tried everything to find balance. it was so hard; especially when my boyfriend came back. i hurt this guy for 3 years before he found balance. he hurt me too. since then, my life has beena twisted love story.