What can I do to win my best friend back?

I have been best friends with a guy for about a year. We were friends with benefits, and as he wishes with absolutely no commitments. He has been with numerous girls since. I am good friends with his brother too. Lately I had been blown off by my best friends so he could chase after his one night stand (self admittedly). I have been going through a really rough time and started hanging out with the other brother more seeing as my best friend was not around. Unfortunately, I crossed the friendship line with the other brother. When asked by the best friend I answered honestly. Now the best friend says "I do not hate you but that does not mean I want to hang out with you". I feel terrible that it happened but I do not feel like it should ruin our friendship. What do I do?