Apparently, as early as the age of twelve, she was driven by lust, until she had a conversion in Jerusalem.
Deciding to repent and become a hermit, and being under the care and direction of Mary, Mother of God, St. Mary of Egypt left all with only three loaves of bread, after receiving forgiveness in Confession. St. Zosimas met her and gave her Communion on the day she died, after she spent fifty years or so in the desert making reparation for her early life of serious sin. A lion helped St. Zosimas bury her body. She is a saint who overcame her predominant faults in the isolation of prayer and fasting.
Her life was written down by St. Sophronius, Patriarch of Jersusalem. For those struggling with inordinate passions, St. Mary is an excellent patron.
Her dates are disputed, but her death in 522 seems reasonable to most scholars.
Here are the prayers from her feast day, April 3.
Troparion (Tone 8) 
- The image of God was truly preserved in you, O mother,
- For you took up the Cross and followed Christ.
- By so doing, you taught us to disregard the flesh, for it passes away;
- But to care instead for the soul, since it is immortal.
- Therefore your spirit, O holy Mother Mary, rejoices with the Angels.
- Having been a sinful woman,
- You became through repentance a Bride of Christ.
- Having attained angelic life,
- You defeated demons with the weapon of the Cross;
- Therefore, O most glorious Mary you are a Bride of the Kingdom