How do I tell my parents I'm pregnant?

I'm eighteen, almost nineteen, and I just found out this morning that I am pregnant. My dad is a Baptist preacher. I think he'll try his best to understand and be supportive, but he's going to be so disappointed in me. My mom is going to be furious. She can't stand the baby's father and thinks we aren't good together. She's going to be disappointed in me as well. What is the best way to tell my parents? (I have to tell them separately, as they are divorced.)