Help Please

Okay so my bestfriend and I started dating but it didn't work out. We still talk to each other and all but its not the same. I didnt tell anyone we were dating not even my 'bestfriend'. So this was in September, like 2 weeks ago my 'bestfriend' stopped talking to me. Her and my ex started getting along really well, it was that love hate friendship. She loves talking to him. I think she likes him, and today i might have just proved it. She also updated a status that said ' i dont understand how someone can be so annoying but so amazing <3'. I know him very vell and he knows be very well and I know how he reacts when he likes someone. I dont think he likes her but may feel some interest, i mean she is pretty. But he doesnt care about looks, well he does but hes respectful and a very nice guy. Im glad were still friends. Now if my ex and her end up dating i would just break. I wouldn't interfere. But why her? Why my 'bestfriend'? And in the worst moment when me and my bestfriend aren't talking. I don't know what to do.... help.