Sorry for the delay in the answer, I've been a little unwell.
Firstly I think that it's very important for you to be sympathetic to your wifes position. Try and understand that this a difficult situation for her and her upset very is understandable. I think it's is fair to say many people would react in a similar way.
The next thing that I would say is that your responsibility first and foremost is to your wife not to the friendship. In an ideal world you could have both, but that may the be the case here. As awful as this sounds, which do you value more?
I guess as you well know things change when you get married and trying to maintain old friendships in the same way they were before the marriage is not always realistic. I'm not only on your wifes side here, I think you do have a valid argument, the only difference is that you understand this relationship from the inside, your wife sees it from the outside.
Maybe try things the other way round, tell her that she's right, maybe you shouldn't have female friends, but do it sincerely. When you put it like that she might just see that she's being a little unreasonable! So long as you keep pushing though she will probably just dig in more and more and you will just get no where.
