At the very least if you are filing separate returns you have to include your spouse's name and SSN.  If you are in a community property state it gets more complicated.  But why are you filing separate returns?

Married Filing Jointly is usually better, even if one spouse had little or no income. When you file a joint return, you and your spouse will each receive the $4000 personal exemption, plus the married filing jointly standard deduction of $12,600 (add $1250 for each spouse over the age of 65).  You are eligible for more credits including education credits, earned income credit, child and dependent care credit, and a larger income limit to receive the child tax credit. 

If you choose to file married filing separately, both spouses have to file the same way—either you both itemize or you both use standard deduction. Your tax rate will be higher than on a joint return. Some of the special rules for filing separately include: you cannot get earned income credit, education credits, or deductions for student loan interest. A higher percent of your Social Security benefits may be taxable.  In many cases you will not be able to take the child and dependent care credit.  If you live in a community property state, you will be required to provide additional information regarding your spouse’s income.  If you are using online TurboTax to prepare your returns, you will need to prepare two separate returns and pay twice

We're considering filing separately because he has student loans to repay now that he's done with school and when our incomes are combined his income-based repayment amount is considerably more than if only his income were to be counted.

I am going through divorce (no kids, not legally separated).  No contact in a year and a half (filing jointly not an option and unable to access his w-2 info).  Turbo Tax's response was no help. ( Referred to my mother's taxes , I think they sent wrong response to wrong question).  I left all parts (except SS #) blank.  It told me I must mail in instead of E-File. 

I viewed the response you got for your question--I think someone got confused/distracted as your answer was being written; your question had nothing to do with your mother. ( ! )   However, if you do not have your spouse's SSN, the part about having to file on paper and mailing the return is correct.  If you have access to a previous joint return you could find the SSN.  It would also be on a transcript of your joint return available from the IRS:
<a rel="nofollow" target="_blank" href="https://www.irs.gov/individuals/get-transcript-faqs">https://www.irs.gov/individuals/get-transcript-...>

Did have and entered in his SS#, but did not have info on what was on this year's tax return as requested (exemptions, AGI, etc.). I assumed he filed standard (not itemized) deduction as he has never itemized in 30 years.

If you filed joint last year, your AGI is the same figure for both of you.  (form 1040EZ, line 4; form 1040A line 21; form 1040 line 37)  Without an AGI to put on your 2016 return, you will not be able to e-file.  You say no kids, so he only has his own exemption.  A suggestion:  if you mail the return, use a mailing service that will provide you with a receipt or tracking so you know the IRS received your return.  It takes about 4 weeks after mailing to be able to see anything about your return on the IRS site.  Good luck!