That’s not frustration or desperation, it’s a threat. And honestly it’s a bitch move to pull on your kids. It’s a vicious thing to say to a kid, kids see their parents as their whole life, all forms of security, happiness and comfort stem from their parents for a long time. And to have the person you are completely dependent on say “I can be rid of you” is frankly vile. And one of the foundational blocks to my general lack of relationship with my mother today.
I didn't suggest it should actually be said.
If you've never been in that kind of emotional state, you're one of the lucky ones...