If you want to keep the cheating heart, and you can’t get away from her, then why not ignore her? No sex, cuddling, or nice words.
That’s the only tactic I’m left with.
Another thing is to cheat back subtly – you know, what’s been done to me.
Oh, what about Brenda, wasn’t she looking so hot today? But how to do this effectively? Ideas? This could be fun.