Is it "James' wife" or "James's wife"?

[nesteaschool]

Bob and I both know James. We've lost contact in a long time, and when I met James, he's already married. One day, James took his wife, Mary, to my house; so I've known his wife, but Bob hasn't. When I and Mary were going shoping, we met Bob. Should I say "This is James' wife, Mary." or "This is James's wife, Mary." in order to introduce Mary?

[Red5]

I believe it should be "James' wife".

[nesteaschool]

thank you very much