"My aunt had gone silent."
Translation:Ma tante s'était tue.
tue is the feminine form of the past participle of the irregular verb '(se) taire' which means 'to go silent'. It is similar-looking but not actually related to the word tuer whose past participle is tué.
If my aunt had taken her own life, the French sentence would be "ma tante s'était tuée".
No, no, this has nothing to do with dying. The verb here is "se taire" which means to go silent. The verb "tuer" is to kill.
The past participle of se taire, tu(es), looks similar to the past participle of tuer, tué, but they mean different things. Check for the accent.