Overnight...

You have a family. You live like a human.
I understand the only way to do that is with blue kryptonite.

I didn't put it on overnight. (He hadn't put it on immediately?)
When I first arrived, I wanted to be alone.

Why?

Sometimes a scientist can get caught up in theories.
My work led to the creation of the brain interactive construct. I realized
much too late that my technology could lead to the destruction of worlds.

So, you came to earth.

To clear my conscience. I planned to study the yellow sun's effect
on Kryptonian minerals but discovered it was the sun's effect on me that really mattered.
I could save the human race.

You gave up your abilities for Grace. It must have been a difficult decision.