Confessions: I am living with HIV, how do I confront my husband?

I have a 4-year-old son and I am 5 months pregnant. A month ago on my regular clinical visits, I discovered that I am living with HIV. The doctor talked to me at length and encouraged me to tell my husband. Up until today I have not had the courage to tell him about this. I have never been unfaithful to him and we tested negative several years ago. I am depressed and worried about who is going to take care of my children when we are dead. The biggest problem is telling him about this. Knowing him, he will claim I am the one who infected him especially because I travel a lot for work and he does not like this. He has even influenced his family to talk me into resigning because of his insecurities. Please help me deal with this. I know he will put all the blame on me and chase me away.