BTB by Suicide
Read a story where husband tells wife's lover "Next time I see you in my house one of us will be leaving in a body bag"
Elderly couple husband has medical problems that caused impotence. Wife gets frustrated and takes a lover. Husband finds out he is going to die just before catching his wife and lover. Most of Family (adult children, siblings, and in-laws) sides with wife so she continue seeing lover. Does not tell anyone about pending death. Final humiliation wife invites love her to family gathering. Husband pulls gun and blow his brains out in front of everyone. How does family cope guilt trip, blame game, or any other mental issues arise.
Husband cannot kill anybody else is that will give sympathy. Bonus points if husband makes financial arrangements for his half of savings get donating to charities before killing himself.