You did well with the explanation of what a wedding ring means, but you should have turned it on your W from there, because it's not up to you. IE: "That's a good question and I don't know the answer. You'll need to ask mommy why she's not wearing her ring."
You saying, "she needs to put it back on" is a controlling statement.
Also, now that I think about it, don't get into power struggles with a kid, IE: "he was trying to get back at me". You are an adult. You need to be authoritative and not get into little tit-for-tats with him.
ME: 38 BF: 40 T: 10y, no kids, no M (by choice) BD: 7/14/14, BF admits to PA, wants out, lies about new R. 10/1/14: I move out, BF lies about move in with OW 12/4/14: OW confronted, reveals all the lies