Boyfriend Bestfriend

My boyfriend has a best friend that I'm not a big fan of. He knows this so I just stay in my lane and he makes sure she stays in hers. She's not mentally stable and is pretty much all over the place emotionally. Last night she told my boyfriend randomly that she took all her sleeping pills and is on her way to the hospital. Naturally this concerns my boyfriend and he starts worrying. I'm worried how her doing this will effect my boyfriend ( this is not the first time she has done this). I of course don't want to see him in distress and wonder what is the best thing he can do.