When you discover your spouse already a hidden child

Getting hitched with the man or woman of your dreams has always been the most fantastic and memorable moment for most couple. That moment when

you say i do and you know in your heart that it is settled. Then you move in with your spouse, start a new life together and everything working smoothly.
Then years down the line you start noticing suspicious activities indicating your spouse may be hiding something from you. That's when you enter the 'incognito"  mode and you find out that the impossible has happened  Your spouse has a child outside wedlock!

Now the deed can't be undone. Would you continue with the marriage or would you call it quits on the grounds of infidelity?