Mild tweaking, major reconstruction or total de/reconstruction

Aaargh! So annoying! I hate when I've sent a book in and then happen upon an idea that will greatly affect it. So now I'm second-guessing the ending of Onion. Oh, that horrible word "second-guessing." (Okay, it's two words. It's one phrase, though.)

Sure, I've been mildly tweaking it since I sent out the submission to Delacorte. And I'm fine with the story so there's no need to utterly deconstruct it or reconstruct it. But now I'm wondering...yeah, the dreaded missing scene has popped into my mind. Shouldn't I have a scene where my main male character ponders suicide?

Okay, I suppose I could add it in and see how it works.

Ah, life...always giving us these decisions: mildly tweak, major reconstruction, or toss it entirely.

Whether it's a relationship, a manuscript, a money pit of a house, a business, a pregnancy, a car, a philosophy. Suddenly bingo --> this choice: tweak, reconstruct, ditch. Aaargh. Why did this missing scene have to pop up in my head now, though? Way after I've sent it into the publisher. Will think about it. If it seems necessary to the book -- as if the book has needed it all along-- I guess I'll do it. Will spend the next few days pondering it. While I ponder what to do with this house of ours: mildly tweak, major reconstruction or ditch?