If I pay child support, so I do not receive a refund, I would file separately from my wife correct?

[DoninGA]

Child support payments are not entered on a tax return, neither paid or received.

If you are legally married and living together you can only file as Married Filing Jointly or Married Filing Separately.  You would want to file as MFJ even if one spouse has little or no income.

[MayaD]

If you are worried about getting your refund seized when filing joint return, you can file Form 8379 Injured Spouse Allocation along with your joint tax return.  

Per IRS The injured spouse on a jointly filed tax return files Form 8379 to get back their share of the joint refund when the joint overpayment is applied to a past-due obligation of the other spouse.

How do I file Form 8379, Injured Spouse Allocation?

[Hal_Al]

Q. If I pay child support, so I do not receive a refund, I would file separately from my wife correct?

A. No.  As @MayaD  explained, there is a procedure  that allows you to get the benefits off filing a joint return, that prevents the IRS form taking your spouse's refund to satisfy your child support debt.