Yeltabmit,

Being a man is about serving the greater good for all the people in your life.  Regardless of WHO the mother of your child is... you have a responsibility to provide for that child.  Better that you be IN the child's life instead of having the child grow up fatherless.  Money is NOT the the only answer.  A child needs a fathers guidance.

So of the three people involved...  Your Wife, Your Mistress, and your Child..  You best be doing right by ALL THREE.

Your Wife... if indeed you both still have a relationship and both still WANT a relationship... is your first priority.
Your CHILD... is your 2nd priority.... unless your wife is soon to be your EX wife.
And for the child's mother... you should do right by her as well.

This does not mean that you give them all everything they ask for...  but you provide them with what they NEED...not want!

Hope this helps..
David