I definitely think there might be a language /cultural barrier here.

It’s a popular saying everywhere “insanity is doing the same thing over and over again and expecting different results” it doesn’t mean you are calling a person insane. It’s more of a metaphor. It’s like if someone keeps a diet of pizza and ice cream and continually says “ I don’t j sweat and why I’m not losing weight “

It means every time you let him back with his words you hope something is going to change but it doesn’t. It means you have done the same thing multiple times, but keep getting the same result.

And there is a lot of truth in it for all of us and not an insult, I promise you.
I was surely guilty of it myself. I’m not insane ( well, that’s debatable, lol) but I just stopped doing all these things that just ended up hurting me and didn’t yield the results I had hoped they would. Did my ex come back? No. But I got to quite hurting myself and sacrificing myself .
And it’s a good thing you have realized that all the codependent picking up of the pieces that hurt you greatly isn’t going to get you what you hope for and you have finally decided to stop sacrificing yourself