Refinancing without a husband now
You must change it because it would be the truth. When asked if you had a divorce, write an explaination letter of the truth. Your prvious loan officer shouldn't have put you as married on your loan application in the first place. This is your best option.

Second FHA Loan on a second mortgage?
Yes, it is possible.

Should I do FHA or conventional when I have more than 3.5% downpayment?
You should do a 5% down conventional loan with no MI.Call me with questions800-385-3657