Known for her character, Florence, in the SABC 3 soapie, Mnumzana, 37, says she has relied heavily on the support of a close friend, Pamela Nomvete.
She says her emotional wounds are healing and now she wants to help other rape victims.
In an exclusive interview with City Press, she said the first incident happened when she was 10. A family elder raped her. At the time, she felt so ashamed she kept it a secret.
She said she never even told her mother, Kedisaletsi Mnumzana.
The second incident took place when she was 13. The abuser was also a relative.
Then, later in life, she claims she was raped twice by a person she was "intimately involved with".
In another incident, in 1993, a stranger attempted to rape her in Soweto. She said she had been working as a teacher at the time when a stranger attacked her as she entered the school's premises.
A group of teachers and pupils came to her rescue after she screamed for help, she said.
When not lecturing drama at the Fuba school of arts or shooting an Isidingo episode, Mnumzana conducts motivational talks.