["I'm in a really awkward position. My best friend is cheating on his girlfriend, and my own girlfriend is telling me I need to speak up and reveal his secret. No idea what to do, and I'm disappointed in my friend, too."]
That's horrible. I'd talk to your best friend and tell him how you feel firstly.
I'm a really awkward position. My best friend is cheating on his girlfriend, and my own girlfriend is telling me I need to speak up and reveal his secret. No idea what to do, and I'm disappointed in my friend, too.