Severance offer, what should I ask for? - any advice?

I was offered 12 weeks of severance after 12 years as a marketing coordinator, and I have a few days to sign. I worked as a marketing coordinator before this. There is a non-disparagement clause. Should I see a lawyer?

Thanks for writing this out. I went through something close to it 10 months ago, and it settled down once I kept a simple log of every call and form.