My Secret Girlfriend Is Pregnant, She Wants To Tell My Wife...Please What Advice Do Have For Me???

"Please I need help, I got married in June but before I got married to my now wife, I had a fling with a girl I met in South Africa when I went for a vacation in South Africa. 

Now she called me to say she's pregnant and she's blackmailing me threatening my marriage, I don't know what to do, I don't know if I should tell my wife cause the lady in South Africa said if I don't pay her some amount of money that she's going to tell my wife." - this guy should just tell the lady he has no money to bribe her but can marry her as second wife. Lol!