The way you've handled this latest revelation speaks to your intergrity and strength.
To handle a bombshell like this with such grace definitely encourages me to follow in your foot steps no matter what happens in my sitch.
I can only imagine the feelings you are going through as your process the last 20 years. Rest assured, you will come out of this so much stronger and with the recipe to make your next relationship a wonderful one.
Keep being strong for your boys, they are watching. As long as you can show that life does indeed throw us major curveballs, it doesn't have to destroy us.