I Don’t Want My Friend To Get an STD

My friend’s boyfriend is a cheater, I can’t stand him.  So I had caught my friend’s dude cheating on her.  Like the good friend I am, I told her about it as soon as we got around each other.  She decides to confront him in the car while we were all riding together.  Not only did she confront him, but she asked me to verify what she was saying, basically letting him know I was the one who told her.  I didn’t care that much because she is my friend and I don’t really care how he feels about me.  But of course they are still together and when I come over it is super awkward.  He has even been disrespectful towards me & called me out of my name, also goes around telling lies about me in the streets.  I told her that I wasn’t going to tell her ever again if I heard about him cheating on her.  Long story short, here we are about 7 months later and my people told me that her dude is cheating on her AGAIN with this female who for sure has herpes.  I know for a fact this girl has herpes, and now I’m in a situation where I don’t want to get involved but I also don’t want my friend to get herpes (if it’s not already too late).  I need some advice.  What would you do if this was your friend?