Best friend or boyfriend?

So I'm in a bit of a complicated situation at the moment. My Bestfriend moved to another state two months ago. We've been best friends for 11 years. I love her to bits. We have or well had a great relationship. I could tell her anything.
I've been dating this guy for the last four months. But he goes to boarding school in another state as well. So it's a Long distance relationship. So the relationship is still pretty new. But I feel like I've known him forever. The first three months were amazing. Everything was perfect and we decided to go all the way. We were both each other's firsts. I trust him a lot. And he's a great person. He's very supportive and he stays up nights talking to me on the phone and counselling me because I have a lot of issues at home. The first three months were beautiful. And I'm so in love with him. But since he went back to school, we've been having a lot of arguments. Idk why. It might just be a phase. He has a temper and sometimes he says things that he doesn't mean when he's mad. Some of the things he said were hurtful and that's when I turned to my Bestfriend for comfort. But the thing is he apologises the next day and I don't doubt that he loves me immensely. Like I get it. No ones perfect. I can be very difficult and I understand why he gets mad. He's concerned about my safety because I drink recklessly and I don't eat enough. That's where most of our fights stem from. So when he gets mad he says hurtful things to me but he's never had any wrong intentions.
So when I told my Bestfriend about all this , I strictly told her to not to bring it up with anyone else. But one day she decided to message him. And it was a terrible rude and hateful message where she called him a pathetic excuse for a human being, sick and psychotic. She went to the extent of telling him that he's manipulating me and ruining my life and that I deserve way better than him and that she'll make sure I find someone better.
My boyfriend was broken. I had to hear him read this hateful message on the phone and I heard the way his voice was quivering. I felt terrible. Every couple has heir problems. Yes he's said a few hurtful things to me when he was mad. But even I've put him through a lot. And if I didn't think the good was worth the bad, I would've ended this relationship. But the good is so beautiful. And I love him so much. I'm not the kind to give up on people so easily. And he loves me too.
I'm really mad at my Bestfriend because it was not her place to tell him all this. She doesn't know enough about my relationship yo have said such hurtful things to him. And she never apologised and says she doesn't want to take what she said back. He's really hurt. And if one of his friends had told me something like this, I know he'd stick by me and cut that friend off. That's where I'm stuck. My Bestfriend made a rash and stupid decision because she was concerned about me. But even though her intentions weren't wrong, that doesn't change that what she did was terrible. And Idk how things with my Bestfriend will ever go back to being the same. Can they? How can I let it if she said such horrible things to my boyfriend? If I mend things with her, it would be making me a bad girlfriend. This is something I realised after I switched roles and put my boyfriend in my place. If he was still buddy buddy with his Bestfriend after his bestfirend told me things like this, I would come to the conclusion that I'm not a priority in my boyfriend's life and hat he doesn't love or care about me at all and I would've definitely ended things with him.
I'm ignoring my Bestfriend for a while but my boyfriend and Bestfriend are both returning in October during the same time. I don't know what to do. I'm stuck in the middle. She's forced me into a situation where I have to choose between her and him, even if she didn't intend on doing it. Who will I hang out with ? Her or him? Even if I distribute my time , spending time with both individually , I'll still be wronging my boyfriend by completely disregarding the fact that she hurt him so much. And I'm pretty sure my relationship with him will fall apart if I just disregard what she's done and hang out with her once she's back in town. And I can't blame him if he lets that happen because like I said, I would've felt terrible too and ended things with him if he still chose to associate with the person who hurt me so much. So now I'm stuck. Yes she's my Bestfriend of 11 years. And I've been with him only 4 months. But time can never be a measure of anything. I've never loved anyone the way I love him. And no ones made me feel as happy as he makes me feel. No ones given me as much love as he's given me. And I'm not ready to let him go. But how can I choose someone over my Bestfriend of 11 years? If I forgive her then that'll make me a terrible girlfriend and my relationship will fall apart. She even refuses to apologise to him. But even if I forgive her, I'll remember that she's the reason I lost my first love. Please help. Idk what to do

Paragraphs please......a wall of text is way too difficult to read and most people won't bother to read it.