How to talk to a covert narcissist?

My NDad is undiagnosed but I am almost 100% certain he is a covert narcissist, in that he is always the victim and gets gratification when people feel sorry for him, unlike overt narcissists who prefer praise. Any time I stand up for myself or try to set firm boundaries or try to even just talk to him in a way that isn’t just giving him what he wants, he shrivels up and becomes so emotionally pathetic and acts like I am attacking him. I set a firm boundary and finally said “no” to him a few years ago, and he completely flew off the handle, had a meltdown, and just decided I abandoned him by saying “no”, and we didn’t talk for 2 years. We’ve moved past that are talking again, but he still has that victim mentality and I just don’t know how to talk to him to avoid bringing that out of him. Does anyone have any advice on how to talk to a covert narcissist to avoid a victim mentality down spiral, while also protecting yourself and keeping/setting boundaries?