The Official Website of Grand Ayatollah Makarem Shirazi

If a Muslim woman marries a Christian man, their marriage is invalid and they must separate. If they have a child together, in case they knew that their marriage was invalid, their child is considered to be illegitimate and does not inherit from the woman. However, if they did not know that, their child is regarded as legitimate. Another important point is that if a woman converts to Islam, but her husband does not, they must separate, though she cannot get married again until a time period equal to the divorce Iddah is passed. If during this time, her husband converts to Islam, they can remain married. Otherwise, the woman can marry another man. But if the woman has a serious problem, she can stay married to the man for as long as she has to. Finally, if a man converts to Islam, but his wife, who is not of the ahl al-kitāb, does not, precaution demands that the man wait for a period equal to the Iddah of death. If at the end of this time his wife has converted to Islam, they must recite the marriage formula and then they can continue living together. Otherwise, they must separate. And two quick miscellaneous points. Getting sexual pleasure from one's wife without intercourse is permissible during her monthly period. Whipping and physically hurting one's wife for sexual arousal is impermissible.