Sayyiduna Abdullah bin Umar (may Allah be pleased with them) used to say: If a slave woman is married to a slave man, then she is set free, she will have the choice (to stay with him or leave), as long as her husband has not had intercourse with her after her emancipation.
Imam Malik, may Allah have mercy on him, said: If the husband had intercourse with her after her emancipation and the slave woman said that she did not know about the issue of choice, then her excuse will not be accepted and she will no longer have the right of option.
Hadith Referenceموطا امام مالك رواية يحييٰ / كتاب الطلاق / 1161