Yes I would. Because if I didn’t, then they’d continue to cheat because they’re getting away with it.
If it we’re me, and someone saw my boyfriend/husband cheating I’d hope that they would come tell me right away. End it now before things get worse, getting the other woman pregnant, or he getting an STD then coming back and giving it to me, etc.

I appreciate your concern Angela. You wouldn’t remain silence when bad things unfolds. Otherwise thanks for your comment.