DON'T YELL, but be firm... I am not sure if you should bring the boys into it... But if you do. Keep it simple: I'm done or I know, and our sons will know too... You have to kick her out. She might freak out, cry, beg... You have to walk away from all that.... My hands are shaking as I type this because I remember this part, and as a WW, it's scary... But necessary.
You cannot have a conversation with her. This is where you respect yourself more than you love her. You have to do it this way, hoosjim...
