She's 19, so she should be mature enough to be allowed to do that kind of thing. Lots of things seem really scary or completely different at the time, but from an objective view seem not so bad. If you get caught up in believing your some sick freak that will stunt and deform the way you grow up and you'll be unhappy. Don't worry, it should pass in time, almost everything does. I think a major issue is the taboo of family. Your sister has sex whether you like it or not. You saw some of it and enjoyed it, it was the eroticism of the act. In the tape you probably didn't see your sister, the member of your family, you saw a different girl, because she seemed so much out of place. You know what's right or wrong and I dont think you'd ever make a move on your sis. You had the conscience to come on here which shows you know its wrong. Keep out of your sisters business next time. Unless things are really bad, don't talk to her, it will only make them weird for her. Just keep your mind off it, thoughts will pass in time and always seem more constricting and uncontrollable the more you think them. Don't take anything too seriously, your gunna be ok. Also, much of what you find on the internet about stuff is bullshit. Everybody has different takes on stuff, many are not being serious, and few are actual psychologists. Try an anonymous help line if problems become unbearable. Good luck!
