My best friend doesn't want to hang out with my other best friend?

So tomorrow we're all supposed to go to the beach, and Bestfriend #1 doesn't want to go if Bestfriend #2 goes. They're at odds with eachother because of boyfriend drama, and Bestfriend #1 thinks that Bestfriend#2 has a lack of respect for her. But whenever the time comes for her to stand up for herself, she never does. She just deletes her on facebook. So Bestfriend#2 said she couldnt go, so I let Bestfriend #1 that she probably isn't going, so if she still wants to come it would be fun. Bestfriend #1 said she's going now. Then an hour later Bestfriend#2 says she'll try to come. Now i feel horrible. I'm trying to stay neutral since what's going on between them is between THEM, not me. I have never been there when Bestfriend #1 says that Bestfriend#2 was being disrespectful, and I know from past events that Bestfriend#1 easily overreacts, and takes things in the wrong way a lot. So I never know what truly happened. Bestfriend#2 has always been a good friend to me, and sometimes I feel like she is there for me more than Bestfriend#1, so I defiantly don't want to judge her from here-say, since she hasn't been disrespectful to Bestfriend#1 when I've been around. So yeah, I have no idea what to do. I feel so bad, Bestfriend#2 even told me she didn't have the gas to go, so I thought for sure she wouldnt go ): I can't say, oh sorry Bestfriend #1 is going so you can't go, because I invited both of them! Just like I said, Bestfriend #1 takes things in the wrong way sometimes, so I know her feelings will be hurt if I tell her Bestfriend #2 is going again. Please help!