How can a girl, who was known for her multiple relationships and falsely claimed to know the unseen, and has now repented, overcome her anxiety about her bad reputation and become a righteous girl?

Allah accepts the repentance of those who sincerely and devotedly repent, and He transforms their evil deeds into good ones. Therefore, you must be sincere in your repentance and increase your good deeds. Allah the Almighty said: "Your Lord has decreed upon Himself mercy: that any of you who does evil in ignorance and then repents after that and corrects himself - indeed, He is Forgiving and Merciful." (Al-An'am: 54), and He also said: "But whoever repents after his wrongdoing and makes amends, Allah will accept his repentance. Indeed, Allah is Forgiving and Merciful." (Al-Ma'idah: 39), and He further said: "And whoever does evil or wrongs himself but then seeks forgiveness of Allah will find Allah Forgiving and Merciful." (An-Nisa: 110). Moreover, Allah extends His hand to accept the repentance of the wrongdoer at all times. You should also associate with committed individuals, read books on heart-softening topics, learn from the stories of those who repented, and trust in Allah's promise.