How do you know when your marriage is over or this is abuse?

I have have recently had a problem of my husband demanding sex and making me feel inadequate if I was not in the mood. He gets quite angry with me when I refuse. It has had the effect of making me want sex even less. I feel anxious and as though I have a problem. I am open to the fact that perhaps the problem is mine. I have had a difficult marriage and have tried very hard to make it work for the sake of my children. I last refused sex when my eldest child left school, it was such a happy day and I thought I had achieved something positive in bringing my eldest child to this point. That night my husband demanded I go to bed early (he always does this) and repeatedly shouted downstairs 'are you coming to bed'. I did go to bed, but in the event he got quite angry and I tried to explain that I was just getting quite anxious about the whole thing, but this made him even worse. I felt worthless and a failure. I ended up sleeping on the sofa. I felt vulnerable and afraid to sleep in my own bed. The next day he was apologetic. I am worried about his true nature and controlling temper. His mother died after 40 years of marriage to his father and I always thought they were happy. 1 week after his mothers death he cleared all her belongings out of the family home, 6 weeks after her death he moved in with another women. sold the family home and used the proceeds to buy a house for his new female partner. I am concerned about my husband, his temper and whether he is shallow (or a good actor) just like his father. It may seem overly dramatic but sometimes I feel he does not care about me at all, he is shallow and cares only about outward appearances. I do not want to feel I am wasting my life on such a person. I am very depressed at the moment so this is perhaps altering my judgement thinking