The margin is tight, and there is risk, but it really depends on what your other options/opportunities are. If you could get another job that would pay you more than you make now, that would be a simpler option, but it sounds like you aren't convinced that is possible.
Pros: You are in a tight situation, and this is potentially an opportunity to improve it considerably from where you are now. If you buy the business, and the numbers are accurate, you should see an immediate increase in income, opportunity to pay off your debt more quickly, and start saving ASAP for your retirement (Do you have any retirement savings in addition to that $2100?).
If those numbers are accurate, you'd be earning an extra $13k per year (after debt service) based on an upfront cost of $2000 until the debt is paid off.
You already know the business if you've been running it.
If the owner is willing to take the risk of financing the sale knowing you have a tight financial situation, she must be fairly confident you can make it work to pay her back.
Cons: You are assuming the financial risk for the business. But, if it fails you declare bankruptcy. If your net worth is negative as you show, that may not be a bad option. Do you have other assets at risk?
You have to be the owner as well as the manager. Depending on your duties "running the business" now, that may not be much more work than you are doing currently.
If you already run the business, you should have a good sense of how accurate all those numbers are, and know what's involved. Be sure the terms of the lease and the nature of the business make sense - how many years left on the lease, how much is the "rent" set to increase each year, are you going to be losing money for the first part of the year and only making it up in the holiday season, and can you afford to weather the lean months?
Good luck with a tough situation.
Looking down the road 10+ years, do you have other retirement savings? any idea what your social security situation will look like when you are eligible, etc?