How about remorse? Perhaps even that is not the appropriate word here, but do you believe there are any circumstances in life where grief is a natural and even healthy response? If so, why not this circumstance?

I would suggest that if you encounter a situation in life where there's genuine remorse for a choice you've made, there aren't only two options of "celebrate your regret" or "suck it up." There's such a thing as honoring pain without dwelling on it, and if done properly, it actually enables your growth in a way that's healthy for both you and the world. And if so, perhaps it's okay for the world to learn from your growth.