Sisters Tricked Into Anal With Brother

I really need to speak to my older sister about something, I go into her room and tell her that I want to have anal sex with my boyfriend. He is really religious so doesn't want to have vaginal sex until we are married, but I really need some advice! My sister is so shocked and says that there is no way I will be able to just do anal for my first time. I plead with her to help me and she eventually gives in. She bends me over, pulls down my panties and fingers my asshole, to get me used to the feeling of something inside of my ass, but I don't think this is preparing me enough. I suggest asking our brother for some help, I mean my sister already fingered my ass so we may as well get our brother involved too! He is more than happy to help and he gets his dick out but it is so big, i don't know how that is going to fit in my ass! I go and get the lube and prepare to take my brother's cock in my ass. My sister helps guide it in, but its so big it hurts so much! He fucks my ass deep and rough, I can't believe this is what it feels like! I beg my sister to take over, as she has done anal before and maybe she can show me how its done! I guide my brothers cock into her ass and he fucks her hard and deep too, I don't know why she's complaining so much, I thought she would be a pro at this! He fucks her ass until he gives her a big anal creampie! My sister thought she'd be teaching me a lesson, but it looks like we both got a pretty big lesson.