That's the problem with fights with our partners, they know exactly what to say to cut to the quick. Did you tell your wife what telling her meant that to you? It may be that she didn't quite know how important it was - especially since it does not seem to be a common approach of hers, judging by your surprise.

As for the fight - I am not at all surprised she lashed out, even with the heavy artillery. Your wife is not putting you in a difficult position, you are putting her in an impossible one! Your mother has no parenting rights to your children - certainly not ones which would rival your wife's.

Time to create some boundaries: - With your mother - tell her thank you for her opinions, but you and your wife will handle it from here. Make this your premanent attitude. I hope to god you haven't told her you agree with her yet. - With your wife - tell her how hurt you feel. Tell her you understand why she lashed out (I really hope you do), but that you think she doesn't appear to have realised just how crucial your revelation was to you. Tell her how you'd like to 'fight fair' in arguments, and ask her what would be fair for her. - With yourself. Sort out this parenting saga with your wife - between the two of you. Then start being diplomatic but honest with her about your feelings, rather than letting your mother be your spokesperson.