What should I do? Should I divorce my husband?

I have been married for 18 years to a muslim. When we first married he was very moderate but as the years have ped he has become more fanatical and has become an Iman. Most of his spare time is spent reading religious information or preaching in chat rooms on the internet. He has grown a beard for religious reasons which I hate. As you probably have gathered I am a christian. I do not love him anymore as he has done so many things which have hurt me, he always rubbishes me and makes me feel worthless. Even the children do not love him. I want to leave him but feel that I need to wait to the two eldest finish school. One has 2 years left the other 4. He is away 4 days in the week so when he is not around things feel normal. The childrens school is very expensive they are both doing well and I feel it would be wrong to move them. If I left him I could not pay for the school fees and he would not.I do not go out with him unless it is to his Muslim relations. I am very loney and know I deserve better. Everyday I resent him more and feel I am living a lie.