Seemingly supportive sister

My sister is currently 21 and goes to uni so I hardly get to see her, but when she does come home we always have really long talks and we're very open with eachother. I always thought that when I am ready to come out I would tell her first, but now I'm not so sure. I recently told her about my friend who is addicted to masturbating and the porn that one of my friends found on his computer (anal). She said that someone his age shouldn't even be aware of his sexuality and for him to be looking up someone as weird as anal is just sick and twisted. We then started talking about anal, she said she didn't understand why anyone would do it and that it's disgusting and that she would never do it. This kind of crushed me because I was pretty close to coming out to her at that point.

She's always acted very accepting of people, whenever she comes home she has an unprovoked feminist rant telling me about how about how white men are all scum (I know, thanks for that). She even had a friend in highschool who was trans*.

I was considering coming out to her via text after she starts her new term of university because then she wont be coming home for atleast a couple months and she can have time to think about and understand it.

Note: Don't get me wrong, I'm not saying he's addicted as in one a day addicted. He has a routine of 5-10 a day and he tells us about how he wakes up and does it in the shower and then has another when he gets out the shower ect... I seriously think he has a problem.