<human>: Can you summarize the given text in a few sentences?

Here is the story: these two were dating for some time, approximately 2 years, and wound up living with each other. The female of the relationship (my best friend) suddenly left her previous BF (who is now my close friend) for another feller. I suspected some foul play was involved but it wasn't my business to explore. 

Today shit hit the fan and both guys found out that she had been lying to both of them. Her new BF dumped her, her old BF has been sending vindictive messages to all of our close friends. 

I'm really worried about her. What should I do? Keep in mind that I am also close friends with her previous BF.
<bot>: best friend fucked over two guys and now her entire social circle is falling apart. Need help on how to console her.