No, she is not right -- and in fact she's living a life that's very dangerous spiritually because she has deceived herself into thinking it doesn't matter how she lives. But it does -- as the Bible makes clear.
Yes, God has promised to forgive all our sins when we turn to Christ in faith and trust, but we must first repent of our sins. What does it mean to repent? It means to turn from sin -- to leave it behind us and commit ourselves to live the way God wants us to live. There is no forgiveness without repentance! Jesus' first recorded sermon included these words: "The kingdom of God is near. Repent and believe the good news!" (Mark 1:15). The Apostle Paul said that God had called him to tell people "that they should repent and turn to God and prove their repentance by their deeds" (Acts 26:20).
Does this mean we have to be perfect before we can be saved? No; if it did, then no one could be saved, because no one is perfect. But Christ came to cleanse us of our sins, and He did this by becoming the final and perfect sacrifice for our sins on the cross.
Pray for this person, that God will convict her of her sin and bring her to true faith -- a faith that changes her life. And make sure of your own commitment to Christ, for life's greatest joy comes from following Him.