Hoenstly, it doesnt affect you, leave it alone. She doesnt know you, you dont know her. Let her live her life; he told you this in confidence; maybe you're the ONLY person he told. IF she were going to introduce the child to his family, she will do so. It is, quite honestly, none of your concern.
If it were a relative of yours, or, as was said, and army buddy, that would be different; he was a friend and, although your intentions are good, they are misplaced.