Is this horrible of me?

okay so my best guy friend has liked me this whole year. he is litterally my best friend. and ill say i love him but you know in a friend or a brother way. and hed say it back. sometimes i would flirt with him. but nothing big. i would go hang out at his house and he would hang out at mine. he knew my family i knew his. one day he wasnt there when i got to his house only his older brother was. which is the only sibling he has. and so i went and sat on the couch with him then we started talking. and before i knew it we were making out then when my bff gets to his house were sitting on the couch like nothing happned. a week later his brother asks me out and i say yes. but days later my best friend asks me out. i freaked out and spilled that i was dating his brother, now he wont even talk to me or look at me.