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.
First of all, we ask Allaah to protect your religion, increase your zeal in obeying Him and enable you to do what pleases Him. Indeed you did well by observing Hijab and avoiding to study in a mixed school.
If the matter is as you mentioned that your husband does not want you to wear Hijab and he wants you to continue studying in a mixed school, then he is wrong and it is not permissible for you to obey him in this, as there is no obedience to a creature in disobeying the Creator. For more benefit, please refer to Fatwa 88245.
Therefore, you should advise him in a nice way, then if he takes heed, all praise be to Allaah, but if you fear to be harmed if you continue with him, then you have the right to ask him to divorce you even by paying him a compensation. You should try to convince your parents about this, and if they persist that you should continue with your husband as he is, then you are not obliged to obey them, and it is not permissible for them to order you to do something which results in a disobedience. For more benefit, please refer to Fataawa 84942 and 82730.