Im twenty two and pregnant. how do i tell my family?

I don't know how to tell my family that my boyfriend and I will have a little one in 8 months! I live with my grandparents. They're only 66 years old. They're very involved in my life and love me very much. They even like my boyfriend. I graduated high school attended thee yrs of college. I waitress and bartend now and have been waitressing since I was 15. I show great responsibility. My boyfriend is also 22 and is a manager of a drug store. We both make good money. My boyfriend has a child already that he financially supports. They know were sexually active. I'm in a much better situation than a lot of other pregnant young woman! So how do I tell them?! I've always been such a nervous person!