well, you have kids or you don't... in both cases you may at some point doubt your choice (most humans do, for most of their choices). Also, in some case, kids are not really a choice, I know... some want some and can't, some weren't willing some (or not that early) but have them...

In all cases you may "feel some pain" of your situation, at some point. I just wish to point out that happily, you are not in the other situation, which has its pain too.