Advice for someone in the closet.

I've been thinking about coming out for over a year to my family, but when I do get the confidence to do so, I'd imagine how they would react. I don't fully understand what my mom thinks of gay people however I've seen her disagree with it, but I did her upset when gay marriage became legal. I grew up in a family with a Catholic background and was very religious, however my mom and dad had drift farther away and we stopped going to church. My younger sister also had conflicting views with gay people however she said she'd be okay with it. Nobody knows except my friends in school, whom I've started to drift away from, I still want to come out but I need help on how to get confidence and cope if a negative reaction should happen.