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.
If the situation with your husband is as you mentioned, then you should know that this is an affliction which should be met with patience. We have already clarified the excellence of being patient and its importance in Fatwa 88764, so please refer to it.
Nonetheless, returning to Allaah and being on His Obedience and performing His Obligations is the best thing which will help you overcome these difficulties. So you should avoid being negligent about your religious obligations and you should be keen on performing them, especially the prayers. The Prophet said: "The pact between us and them [non-Muslims] is the prayer, so whoever abandons it is a disbeliever." [Ahmad]
The jurists differed in opinion in relation to a wife serving her husband. Anyway, this matter should not cause a misunderstanding between the spouses. So a wife should not refuse to serve her husband. Likewise the husband should not exaggerate in exhausting his wife for his own interest and neglect helping and understanding her. Spouses should treat each other honourably and help one another.
As regards when your husband calls you to bed, you should obey him unless you have a religious excuse, like being in menses, in postpartum bleeding, sick and the like. However, if you are harmed by that, your husband should not oblige you.
Therefore, we advise you to discuss this matter with your husband in a good and nice manner and seek the help of the pious and righteous people in necessary. If things improve, all perfect praise be to Allaah, but if the situation is still the same and you fear any harm, then you may ask for divorce because of the harm, and you have the right to take the matter to an Islamic court but you should not hasten to ask for divorce until you compare between the benefit of staying with him and the benefit of divorce.
Allaah Knows best.