1,683. Adultery

Hilchos Ishus 24:17

If a man sees his wife committing adultery, or if he was informed of it by one of his or her relatives whose word he accepts, then it is prohibited for him to engage in marital relations with her and he is obligated to divorce her. He must pay her the value of her kesubah unless she admits to committing adultery; if she does, she is divorced without receiving the value of her kesubah. Therefore, the husband can require her to take an oath while holding a holy object that she did not commit adultery while they were married, after which she can collect the value of her kesubah. He cannot obligate her to take an oath regarding other matters except by bundling it together with this oath.

Hilchos Ishus 24:18

If a woman tells her husband that she committed adultery, she is not believed because she might just be attracted to another man (and is therefore trying to get divorced) but she does lose rights to the baseline amount and additional sum of her kesubah, as well as to any property that was destroyed. If the husband believes that she is telling the truth, then he must divorce her. The court cannot force a man to divorce his wife unless two witnesses testify that his wife committed adultery in their presence.