Should I have told my friend's husband that she was cheating on him?

I told my friends husband she was cheating on him.
He’s a marine, he moved her out to Cali so they could live together. She stopped talking to me completely and deleted me off everything (Facebook, Twitter) and I became suspicious. I easily figured out she was cheating on her husband. So I told her husbands best friend (since I’m not really close to her husband) and he figured the whole thing out. He’s thanked me many times for bringing this to his attention, and honestly I’m glad I did. He works so hard for her so she doesn’t have to work and can go shopping all day.

I don’t personally care that our friendship is done. She’s not really a good person. We were best friends but she’s a compulsive liar, and a real gold digger. I’m more concerned about doing the right thing than a bullshit friendship. I really just felt like he didn’t deserve to be lied to and cheated like that. BUT, does my telling her husband make me a bad person?