How can one forget a former fiancé, despite the breakup due to his misconduct?

Fill your heart with the love of Allah and occupy yourself with what benefits you, such as knowledge and righteous deeds. Strive in reciting the Qur'an and reading beneficial books, such as books of the Sirah (Prophet's biography), biographies of scholars, righteous people, female Companions, and female Tabi'iyat (followers of the Companions). Associate with believing sisters, so that you may forget this man.