What do u do when ur crush likes u and know and goes out wit ur best friend and you still like him?

one day my friend called my crush and asked if he liked me and he said yes and i told him i liked him. and then 3 weeks later i went 2 my friends house with him and 1 of my friends (sorry 2 many friends) and she wanted us to play a game and my best friend and my crush kissed, in front of me my best friend said she was sorry and i forgot it . then a couple days later he asked her out in front of me. and the worst part is i still like him. i cant get him out of my head (but i trust my best friend she is like my sister and she said she was sorry) i don't know what to do.... help me i don't want to lose my friend of my felling for him...