It's driving me crazy i cant keep my baby a secret from the baby's dads family?

my ex and me had a 2 night stand he has a girl friend and i know that was very wrong , but now i am 14 weeks pregnant and he is keeping it a secret from everyone and it is taring me up inside i feel so bad for the other women does she have the right to know is it my place to tell her and i do not want him i want him happy is all i want his women happy i do not know her i hate hurting people i love my baby i am having but i do not think i should be the only one paying for this like maybe he cheated on me the whole 3 years we dated maybe this is what he does he seems so faithful so sweet such a nice guy would do anything for any one but may be it a shame maybe he is this cheater that womanizer women please help i need some opinions