Severance offer, what should I ask for? (update)

My manager said the package is final, but the letter gives me time to review. It has been weighing on me all week. There is a non-disparagement clause. Should I see a lawyer?

An hour with an employment lawyer cost me a small fee and made me feel much safer about signing.

Thanks for writing this out. I went through something close to it last year, and it got easier once I kept a simple log of every call and form.