Sex and pregnancy

So this is my second pregnancy and with my first one my hormones were ragging and I wanted to do it all the time. This one is a lot different. I have no desire to have sex and my husband is getting frustrated. I understand why he has needs and I try my best to keep him satisfied but I don't think I'm doing a good job at it. As he is mad at me right now for turning him down yesterday. I don't know what to do!