"It's going to change my whole life, because the expense (was) not factored into my retirement"

Boo hoo.

How about "factoring in" that you knew this child existed all along. How about "factoring in" that you COULD have set up a bank account for her that eventually could have been making enough interest to cover part of the obligation. How about "factoring in" that the responsiblity to support that child was as much YOUR responsiblity as it was her mother's responsibility. How about "factoring in" that her mother may not even HAVE a retirement account because she's been carrying your burden all these years. How about "factoring in" that YOU could have gone to court to take care of your responsiblity instead of trying to avoid it.

Your life was changed the day you whipped it out, buddy. It just took this long to finally make you come to terms with that.