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. We ask Allaah to exalt his mention as well as that of his family and all his companions.
We have already issued Fataawa: 84471 and 84636 on the ruling of having sex with one's wife while in menstruation. We have also clarified in Fatwa: 90196 what a husband should do if he falls into such a sin. So your husband should fear Allaah and repent to Him and not transgress His limits, as Allaah Says (which means): {And whoever transgresses the limits of Allaah, then such are the wrongdoers [i.e. the unjust].}[Quran 2:229]. Allaah further Says (which means): {And whoever transgresses the limits of Allaah, then indeed he has wronged himself.}[Quran 65:1].
So if you are unable to prevent him from having sex with you during menses when he is obliging you to that effect, then it is an obligation on you to take his matter to whoever could prevent him from this horrible act and warn him. If he takes heed, all perfect praise be to Allaah, otherwise you have to separate from him. Indeed Shaykh Al-Islam Ibn Taymiyyah said: 'If a husband agrees with his wife to have sex in her anus, they have to be divorced as stated by the scholars of our school. This also applies by analogy to agreeing to have sex during menses.' [End of quote]
Nonetheless, you are not sinful about him forcing you to have sex with him during menses as the Prophet said: "Allaah has forgiven for my nation what they do by mistake, or due to forgetfulness and what they are forced to do." [Ibn Maajah]
Allaah Knows best.