Somebody That I Used To Know (Meta)

Five Tuesdays this month means it's time for a super hard meta! The grid should be challenging, even with some judicious Googling. But there's still fun to be had in the clues. And the meta mechanic is on the subtle side. But you will know it when you get the meta answer, which is a word for the termination of a relationship. Apologies in advance for any earworms this puzzle sets off! Answer and explanation: https://www.xword-muggles.com/viewtopic.php?p=95248#p95248

Check out "The MOAT MEOW Mashup Pack" here: https://www.ephesusscroll.com/about/interest4.html. US$10 gives you access to 14 metas that don't always abide by the "rules" of the game. You won't quite know what to expect: asymmetry, 2-letter words, uncrossed letters, sometimes all of those, and sometimes none! One thing is for sure, these are some of the more creative metas my brain has been able to come up with. And there's more: this time there's a mega-meta!