My wife and I made $75,000 in 2018. We have 2 kids as dependents. My wife is delinquent on her federal student loan. Should we file separately?

You can file Form 8379 Injured Spouse form which will protect your portion of the refund from going into the Federal Student Loan program.  You would open this form and fill in the information it is requesting.  You would indicate that you are the injured spouse and file it with the tax return.

This will produce a much better result than filing separately.  You probably need to file a similar form for your state income tax.