All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
It is good that your husband had repented from that sin. Along with his repentance, he has to pay the expiation which is as follows in sequence:
He has to free a believing slave, if he is not able, then he has to fast two months consecutively, and if he is not able to do that, then he has to feed sixty poor people. This is what the Prophet ordered the Bedouin who had had sex with his wife during Ramadan to do.
As for the wife, she is not obliged to pay any expiation since there is no evidence that enjoins expiation on the wife.
Allaah Knows best.