keeping a secret

My best friend thought a guy we knew had a crush on her, so she always talked down on him. I went out with him a couple of times without her knowing, and eventually slept with him. I didn't tell my friend because she was so full of herself that he wanted her. then one time i was drunk at a party, and i couldn't stand the secret anymore so i yelled next to everyone that i fucked him and went down on him, and that it was the best bj he had in his whole life.