You will include your business on your tax return. Your gross income and expenses are reported on schedule C which is attached to the rest of your return. It calculates your taxable profit and your self-employment tax, which flow to the rest of the tax return where it is combined with all your other income, deductions, and credits. It's perfectly normal to file a joint return when spouses have different types of income. In this case you file a joint return that includes your schedule C side-gig, and both your W-2s, pension or IRA, and SS benefit, along with any deductions and credits.
It is almost always better to file jointly. In very rare cases you may pay less tax filing separately, but you would have to test this to be sure in your exact situation.
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