Was I right to get angry about my maternal uncle gossiping with my mother’s evil second husband?

Overheard him telling her husband that my siblings and I are the spawn of the mentally disturbed (it sounds ruder in the original language). I reported it to my mother who confronted him. He tried to deny and then admitted to it. The uncle was abusive mentally and verbally when we were children and I got very annoyed about the fact that he is giving my family a mental health disgnosis and feeding the enemy with this information. It seemed like the ultimate betrayal.
Was I right to get angry about my maternal uncle gossiping with my mother’s evil second husband?
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