How can one atone for the sin and legitimize the money earned during sick leave that negatively affected female students and the curriculum?

There is no harm in the salary disbursed to the patient, and they are not obligated to postpone treatment. It is permissible to benefit from it if it was obtained through a legitimate means, such as compensated leave. The shortcomings during that period are borne by the substitute teacher. One should not be absent again except for extreme necessity, in preservation of the trust in educating and nurturing the female students.