I don't like swearing, but admit that at times a good "f**k" is all that will do (the word, not the action )
I work in an environment where swearing, whilst not common, it not uncommon either. I never swear at work.
Except once. I can't even remember what prompted it now, but I did use the F word. A deathly hush fell over the office and someone said "oh wow - you must be really angry, because I've NEVER heard you swear before!".
And they've never heard it since.
What "worries" me now is the way that F has become a commonplace, everyday word. So now that it has moved into common parlance, those who need to use a word to shock and offend have moved onto using the revolting C word. I am hearing and reading this more and more, and it utterly makes me cringe.
I wonder what word will become the next one to be used to shock and offend, once the C word takes over from the F word as perfectly acceptable in conversation and in mixed company. I dread to think.
I think the OP has had a bit of a rough ride here. For HER, that use of the language was offensive. So being told to basically put up and shut up is very rude, in my opinion. It sound like she's being told that her feelings are not valid.
I do agree that in this case however, context was everything, and if she had felt, when warned ahead of him using the word, that she didn't want to hear it, she could have politely asked him not to use it. The fact that he apologised in advance indicates to me that he is quite considerate of others' feelings so would likely have found another way to relate the tale.
But as has also been pointed out, she clearly doesn't like him anyway, so I suspect he'd be damned if he did, damned if he didn't.