If your sole proprietorship business is "home based" in MD, then yes. See http://taxes.marylandtaxes.com/Individual_Taxes/Individual_Tax_Types/Income_Tax/Filing_Information/I...
What the above link refers to is a W-2 paid non-resident military spouse. Since you have and operate a business in MD, it does not apply to your business earnings only, assuming you do 'in fact" operate your business in MD.
You'll file as an MD non-resident. Be careful when filling out the SCH C on the federal tax return, and make sure you indicate that you, and only you, own the business. Since your husband's HOR is not MD, you don't want MD taxing his AD/MIL income too, when you get to the state return.