Bros Before Hoes?

Bros before hoes, one of the unwritten rules between guys. But at one point does that rule become less about loyalty and more about doing the right thing. So I have this friend, lets call him Shane, and he's one of my best friends. Now Shane has a girlfriend but still goes out and talks to other females and goes to kick it with them. One of the girls he's talking to, lets call her Jen, has started talking to me just as friends. So as I'm talking to her I realize that she's a really cool girl, but she likes Shane who is a bit of an asshole. Basically to make a long story short I began to feel bad for her because she liked him but he had a girlfriend. So I told her the truth, thinking I was doing the right thing, and told her not to tell him. But that backfired and now he knows that I betrayed him and most likely hates me now, even though she wasn't his main chick.

Now I'm sitting here wondering if I really did the right thing. Should I have let some chick come between me and a good friend. I think I just lost a friend over some chick I just met like a month ago. Idk what to do.

-I'm audi 5 Peace