My sister called me a bad friend because I didn’t call my friends out for being an idiot? (Please read before answering)?

One of the girls I’ve been hanging with who I haven’t seen in a while told me that she did something that will scare her ex boyfriend. She told me she pretended to be a police officer to her exe’s job. I was like, “......Wow you did that?”
She said, “Yeah haha haha. Remember I told you that he has a record for shoplifting? Well I’m going to get him in trouble. Hahaha isn’t that smart.”
I couldn’t say anything. I was like, “He’s going to get it.”
My sister went ballistic when I told her. She said, “That is illegal and she’s being very stupid for doing that! What’s worse is that YOU as her friend didn’t call her out on that. Plus you know about it now and you can get into some serious trouble for that. You need to call her out. Report her.”
I said, “Well thought she was being an huge, boastful idiot. But I didn’t wanna start an argument and she’s my friend and -“
She cut me off and said, “See that’s it right there! You are letting your friend get away with that behavior. If you were a TRUE friend, you would have called her an huge idiot for her actions! True friends call you out on your bullshit. To put it bluntly, you not being a good friend right now. You’re not. You’re a terrible friend for not letting her know she’s wrong. You seem to support that and you need to call her out. You don’t speak up, that is your problem! Can’t be silent forever. Sometimes as being a true friend you gotta give them some tough love.”

See now I feel bad. Thanks a lot sis.