Just to reiterate what others have said it's better to be honest with all parties and own it.
To give you an extreme example, a good female friend of mine hooked up with an ex and became pregnant. She gave birth to a baby girl in October of last year.
To this day the father has not told his family or other daughter (who is 16) that he has a kid. This man is a coward and has resorted to alcohol to deal with his 'mistake' instead of being a man. I feel no sympathy for the guy because he can't own it, blames the mom for not aborting.
Ironically his two daughters, one he's a father to and one he wants to pretend doesn't exist, have the same birthday.