DON position offer / feel unequiped/need advice

I've been a nurse for 27 (yikes) years, in long term care for 17 and a DNS for a little more than 3 years. Did I feel ready? Nope but I knew I could learn what I needed to know. There are books, web sites, and all sorts of other sources of information out there to learn from.
If you're well organized that's a great start. You have to be able to prioritize, multi-task, and see the big picture. You'll need to know about staffing ratios, budgets, regulations..you know what you need to know.
Does your corporation offer any training for managers? My first job as a DNS....they threw the keys at me, showed me the phone and told me the regional nurse would be with me for as long as I needed. Yah...she was in the building for 8 hours and on the phone with someone else for 7 of those. If you know the systems used at the facility that's half the battle.
Don't be so hard on yourself. You should give it a try. Make a deal with the company that you'll try it out for 6 months and if you don't like it they'll find something else for you to do. Good directors are hard to find.

CCM said it all and so succintly!

Get your hands on the State Operations Manual and start learning the regs. Also, join your local DON chapter to network and meet others you can easily reach to ask questions, get to know an MDS forwards and back .. since that is where your money is created. read your company and union (if you have them) P&P or contracts as you will find out that a lot of your job is dealing with staff issues. Learn to delegate and not try to "fix" everything yourself.

Try your local DPH website, the state ops manual as previously suggested;the NADONA website has some books about being a director in LTC. Most of us learned by doing, or if we were really lucky, learned from a smart DNS.

AANAC... for the MDS. You can find the SOM on the CMS website and should also be able to pull up your state regs from your state DPH as CCM stated. Get the phone bbok out and call your nearby counterparts and get their contact info.