Damn you were young!
I came out about my atheism just last year; I’m 48 right now, so it was pretty late in life. I will however admit that I’ve been an atheist at least in thought since I was in my teens.
I, like you Andréa, also didn’t come from a religious family however my family reacted with extreme anger and hatred. My brother pretty much told me that I should be killed for my beliefs because it says so in the bible and my mother essentially took his side in the dispute. My sister (a Christian Conservative and member of the Tea Party) also pretty much wrote me off. As for me I was mostly surprised by their reactions though, I mean religion honestly played absolutely no role in any of our upbringings and we were encouraged to question conventional wisdom, seeing as how my parents were both hippies when I was a child.
Anyway, my family now pretty much wants to have nothing to do with me because of it.