The Result of Stringing Along a Husband with a Mistress for Three Years. ～It's Too Late Now Even If He Says He Wants to Start Over～

My husband and I have a marriage of convenience. Even though he has a controlling habit, he's been keeping a mistress for three years, so I never had any affection for him. However, I left things as they were since getting a divorce would be bothersome. But one day, I discovered that my husband's mistress was trying to kill me. Not that I care about my husband anyway. But that's just... you know? Shall I teach them both a lesson? ※This is a resubmission of a short story collection piece for a contest. Thank you for your consideration.