The status of a non-Muslim’s marriage after she reverts to Islam

If a non-Muslim woman accepts Islam and her non-Muslim husband does not accept Islam, the woman will have to observe the Iddah period of three menstrual cycles for a menstruating woman or three Months for a non-menstruating woman or if she is pregnant, then until she gives birth before marrying a Muslim man.

If her husband does not accept Islam before the termination of her Iddah period, her marriage with her non-Muslim husband will terminate and she is free to marry a Muslim man. (Shaami 3/191)

And Allah Ta’ala Knows Best