It would not have mattered if you were "nicer," I'm afraid, simply because of the nature of brainwashing, but then again, there is the saying about attracting bees with honey.
You said and did nothing to deserve being shunned. You simply disagreed with her POV and shared some facts and anecdotes that put the Society in a non-preferential light.
Your mom clearly is too brainwashed to process COC; perhaps she'll "get it" later on. I agree that you have no aplogies to make, and did not intend to suggest that by my interpretation of the article she sent.
My interpretation of the article she enclosed is completely different from changeling's. Maybe what changeling suggests is the case; however, my experience with that kind of thing - my mother is also a highlighter - is pretty much what I said. Most of the JWs I have known are just as quick to apply the "admonition" to others as to themselves.
Anyway, I hope your mom softens up a bit, for your sake and for her own sake. It is sad that she is alienated from her kids.