My Husband Hates Me and My Son

I have been married for 2 years to a man that I thought I knew. I have a son from my first marriage and my current husband has two boys from his first marriage. We have a daughter together. My husband has turned into someone I don't know. He says very hurtful and mean things to me and my son. He was wonderful with my son in the beginning, but now he is mean and pick at everything my son does. My son just turned 7 and is a normal 7 year old boy. Please help, I don't know what to do.