When Jesus changes our heart and we begin to live a new life, do we completely forget what happened before? No!! We use that to share how great he is and so others will believe. After Jesus talked with the Samaritan Woman and she realized who he was she shared the story. John 4:39 "Many of the Samaritans from that town believed in him because of the woman’s testimony, “He told me everything I ever did.”
Don't live in the past but share what God has done in your life and how you were dead and now you have life!