Job One: insist on DNA testing.
Job Two: Get a lawyer. Learn what you will need to do if the roll of the dice comes up as baby daddy for at least one of them.
Job Three: Talk to your wife. Explain there is a possibility but you are checking and that you will do the right thing if required to, as the child(ren) is/are innocent.
Do all of these things at more or less the same time. That is, don't leave your wife hanging while you wait for the results of a DNA test or for a lawyer to call you back. Tell your wife so she's not blindsided if it turns out you are the daddy and even if you're not, so she knows what you have been dealing with emotionally.