I received money from AFLAC in 2015 . AFLAC sent me a tax form only showing the interest they paid me. Do I have to pay taxes on the rest?

These benefits would not be taxable if you paid the premiums yourself and didn't take a deduction for them. If your employer paid the premiums or if you paid the premiums with before tax income, you would pay tax on the benefits, and you would receive a W-2 for the taxable amount.

See this link to AFLAC's Frequently Asked Questions: 

http://www.aflacgroupinsurance.com/customer_service/faq.aspx