Told I owe money back on my benefits after 4 years as a store manager

I received a letter saying I was overpaid about $1150 on my claim. There are 4 people counting on me, so I am trying to be careful. The letter mentions an appeal window and a repayment plan. Who should I talk to first?

I asked for a waiver and a plan in the same call, and they gave me both forms. It was less scary than I expected.