<human>: My [26F] best friend, Julia [27F] is having an affair with a man, Todd [M26] in a serious committed relationship. I've been friends with Julia several years, she's known Todd for a couple years, and their "affair" has been going on for several months. 

There's an obvious consensus that Julia is balls deep in the wrong. For whatever reason, she's still in love with this loser and keeps going back and forth with him. I love my friend, but what she's doing is so shitty and horrible and there is an innocent victim involved - Todd's girlfriend. Julia absolutely refuses to say anything to this girl. Her excuses are that it would just hurt the girlfriend more (GF already caught Todd cheating on her before) and that Todd would physically hurt her (reasonable concern, unfortunately). 

This has been going on for months. I'm beyond telling Julia to stop and giving her advice. At this point my only question is if I should tell Todd's girlfriend. I think she has a right to know. Is it the right thing to do? Is it none of my business?

Can you provide a brief rundown of the text in within 3 sentences?
<bot>: my friend is having an affair with a guy in a committed relationship. Neither will come clean. Should I tell his gf?