All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
Your uncle's wife, who is not the mother of your wife, is non-Mahram (marriageable) to you unless there is another reason for considering her a Mahram like the relation of blood or suckling.
Allaah Knows best.