Johnny, as your aunt was raised Catholic, she most likely knows the seriousness of leaving the Church.
There may not be a lot you can do, but do pray for her. The grace to touch her soul and to rnew her faith must come from God.
Continue to be the good Catholic example that you are to your family.
Saint Francis wrote, “preach always, and if necessary, use words”, because he knew that our best way of ‘preaching’ is to give good example.
It can take years before someone returns to the Faith, but your responsibility is to be the good Catholic, the good and kind person you try to be.
God bless you dear Johnny.