Is it permissible for a Muslim man to marry a Christian woman after they both repent from adultery, knowing that she completed her 'iddah (waiting period) for divorce a month and a half after the last intercourse, and is there an 'iddah for adultery?

If a man marries a woman before her repentance from fornication, his marriage is invalid. However, if he marries her after her repentance and after her womb has been cleared by one menstrual cycle, then his marriage is valid. Proposing marriage to her before her waiting period (iddah) from her husband has ended is not permissible.