I had sex with my best friend's frat brother now he hates me... Why??!

ooohlalala
I have been best friends with a boy since I was in the 4th grade. Now that we've spent years getting to know each other, and become inseparable, I can honestly say that I love him. No, I'm in love with him.

We've kept our relationship strictly platonic friends who happen to get along great, love each other and spend A LOT of time together. Despite the fact that I love him [and jokingly (but seriously) ] plan for us to get married, and if he ever wanted us to be together, I'd do it without hesitation, he has insisted that we are JUST FRIENDS and that it would "be weird" so, he dates other girls to my dismay.

Recently, I went up to visit him at his school. I stayed for two weeks and we had a great time. Then, at the end of the trip, all hell broke loose. See, we had yet another "Why can't we be together?!" conversations where he emphasized yet again that he doesn't want to go there with me. At the same time, I overheard him talking to a girl on the phone. And he's my best friend so I could tell that he liked her. Crushed, I decided to be a good friend and tell myself that if I couldn't be with him, I would just be happy that he was happy with whoever would treat him right.

A few days later, I went out to karaoke and to a bar with some of our mutual friends including his frat brother who I've had a crush on for about 2 years now. We flirted and talked and at the bar, I got tipsy. My boyfriend called and asked if I could go to our friend's house because he was at his ex-girlfriend's house which really upset me. At that time, my mind just said, "Fuck it." I was mad that A.) He didn't come out with us when I wanted to spend time with him and instead went to his ex's house. B.) HE WENT TO HIS EX'S HOUSE!

My flirtation with his frat brother went into high gear and he invited me back to his apartment. I didn't want to do it, but I couldn't resist the temptation. I ended up having sex with him.

The next day, my best friend figured out that I had been over there and asked me if anything happened. I lied and said no. But as the day progressed and I thought about their fraternity and how close they were like ride or die brothers, I figured it would be best that I told instead of him finding out later on. The guilt was getting to me, and I couldn't lie to him, so I told.

Well, he flipped out. He said he felt embarrassed, hurt, mad, and betrayed. I figured that he would be mad but I don't know why. As the last few days of the trip wore on, he stopped talking to me completely. I cried more than I've ever cried in my life. We got into a big argument that ended in him crying and telling me that I hurt him, and then he made me find a ride home. I just want to understand why he reacted like this. I need other opinions so that I can understand. I miss him so much. :(

How can I get my best friend back? He said he needs time but I feel like it won't work!
Updates
+1 y
My best friend just sent me a text yesterday saying, "I forgive you, TTYL." to which I responded, "Thank you, love you." and he responded "I love you too." So, things are off to a slow start, but I feel like our friendship can bounce back.
I had sex with my best friend's frat brother now he hates me... Why??!
9 Opinion