Got a denial letter for unemployment, what now? after 14 years as an IT help-desk technician

My claim was denied after 20 weeks of waiting, and the letter says I have a short window to appeal. It has been weighing on me all week. My employer's version of events does not match mine, and I have emails that show it.

File the appeal before the deadline, even if you are unsure. You can gather documents afterwards. That is the one part I would not wait on.