I think the "cool wives" term is really useful. It's not for women (in this case) who genuinely enjoy porn, it's for women who are doing things outside of their comfort zone because they feel they need to to keep a man interested.
So if you're both happily watching porn and it's a positive part of your lives, not a cool wife. If you're watching porn with him, when you don't enjoy it, but are pretending to, then you're being a cool wife, and you need to work on your self esteem and be secure in what you're comfortable with.
So in that scenario, the person who isn't being "cool" is feeling insulted that someone is assuming their choices aren't their own. But the "cool wife" being told that they are allowed to not like porn, they are allowed to see it as a dealbreaker, they can go by their true feelings, could really help them.
Op you can't ban another adult from doing something, all you can do is say "this is my boundary". He then has a choice as to whether he respects that boundary, or it doesn't work for him.
I doubt there are many adults, male or female, who have not seen porn in some form. Not all men watch porn. Not all women watch porn.
It is one of my dealbreakers, for ethical reasons. Dh does not use porn. Not all men do.
It's up to you where your boundaries lie.
If your issues are more down to selfesteem perhaps there are ways to mend that rather than split up over this. Only you can decide what is right for you.
But your friend is wrong to say that you can't leave just because she wouldn't. This is up to you.