If I were to talk directly to any current or future spousal or familial killer I would tell them this:
You may think your wife/husband/intimate partner/family is worthless and unimportant. But what I can promise you is this: once you commit your crime, you have no friggin' idea how much the world can, and often will, get involved in and follow your case of your "unimportant, worthless" family member, sometimes down to a butt lint level.
This won't go away, even if you think it will. You'll be virtually followed, tracked, paid attention to no matter where you go, no matter how many attempts to run. I've seen it take years for some cases to resolve, and we've all seen murders of a decade or more eventually get solved.
You'll never be able to breathe easy. You won't believe the pressure--LE won't quit because there's no statute of limitations for murder, but something all you spousal and familial killers never think about in your planning is once case followers get their teeth in, it's like a pit bull with a bone. It's a hell I'd never want. It shocks every spousal or familial murderer because they can't fathom that their missing "nobody" could be embraced by the world. Surprise! Just ask Scott Peterson, Chris Watts, Patrick Frazee, Leticia Stauch, and hundreds more.
And understand this too: the universe is so mysterious. Even though someone may be gone, their energy remains. They inspire and guide those who seek to bring them justice, "no matter what it takes, no questions asked." And one day, probably when you least expect it, you'll be out and about living your life and you'll suddenly be surrounded, arrested, and thrown in jail, even if it takes years, and even if you're thousands of miles away.
IMO