Seller finance offer letter minus insurance claim

[Brian Mehrhoff]

I'm looking for some guidance. I've been leasing a property (small farm) with the intention to purchase. The owner has been difficult to deal with as her situation keeps changing and its been hard to work out the terms of the purchase. Its been so hard that I never signed a lease because we couldn't come to terms on the sale, which she tried to combine the lease with option to purchase. So over a year into it now. There was an electrical fire that burnt the house. The owners insurance wants a signed lease. I'm not sure I'm comfortable signing a back dated lease. Unsure of exposure of liabilities... I want to still purchase said property as I see value there. The asking price was $320k. Insurance assessed damages at 100k, so I was going to make my offer to her at $220k, she keeps insurance money, I purchase as is, and have her finance. Am I missing anything here? Any pitfalls or huge red flags I'm not seeing?

Thanks for your time