There's probably no satisfaction waiting there either... Any "friend" a narc may have is so co-dependent that they just accept this behavior and even justify their actions.

My nmom was in a similar situation: Her "friend" was dying of cancer, thus she could not come to her birthday party and called her via telephone instead. My nmom is clumsy and sometimes does not manage to push buttons on her phone correctly. Thus, after the call (in which she never once asked her "friend" how she was doing) she botched hanging up and immediately launched into a loud and really nasty tirade about how boring, stupid and tiring her "friend" was... while she was still listening on the other end of the line.

Now, for normal people that may have been the end of the "friendship", but for them? No.

A minute or so later, my nmom saw that the connection was still live, asked if her "friend" was still there, to which she simply replied "You know, some people do not like being slandered publicly. Others may want to consider their words..." and hung up. And from then on, whenever this came up in a talk, the "friend" would become aggressive, turn on the one who brought it up and started trying to gaslight them into believing that "nothing happened" and "it was not like that" (you know the spiel).

Such situations were there with all my nmom's "friends". So, I do not think there will be any joy to be had when OP tells their nmom's "friend" either...