"Excuse me, I need to pause. I have never met you before this call. We are strangers. You demand my attention because you say you need it. To be fair, your needs are no more important than mine. One of my needs is to be treated with respect. Frankly, since I am no longer an employee, I fail to see why you make any demands of me. But because I am polite and want to hear the details about the severance, I will stay on this call for now. However if you continue to treat me disrespectfully, I will drop from the call, and you can email me the details of the severance."
I realize the bravado of the above, but I was in fact laid off one time, and I did assert myself to the owner who at least had the guts to do it himself. A few months later he calls me and asks me to me to return to work to finish the project (not a software project, a building construction project), and I declined and instead told him I would do it on a contract for twice what he was previously paying me. He had no choice, took the offer begrudgingly, and I finished the project, designed another big project the same way, and then moved on with my life.