TWO GUYS AND I NEED HELP

i am currently in a relationship but recently my close friend (who i treat like a brother) just admitted he has feelings for me(we’ll call him A). i love my bf but i’m starting to see things in A that i haven’t seen before. him and i have so so so much in common and get along so well (not saying me and my bf dont) but A and i relate to things on so many levels just with life experiences and who we are as people. my bf is a great great guy and we also relate to eachother but i just don’t know what to do. someone PLEASE HELP IM CONFUSED