Comming out to religious parents! Please help! :)?

Im 15, a girl, and im bisexual. Ive knowen for a while now and its really eating me alive! I go to an all girls school so im nkt going to say to anyone in school because anyone like that gets bullied etc, so im considering telling my best guy friend out of school. My real question is, my parents are christians- they would have a glass lf wine sometimes but mainly their pretty holy. I respet that and i respect their religion, even though im not christian myself. They know i dont believe i god but force me to go to church, which is ok because id rather just deal with it until im 18 etc as i dont like arguements. A few weeks back i was just having general conversation with my parents ( at dofferent times) and the subject of homosexualaty came up. My parents both believe you chose to be that way and i disagreed but thw subject was quickly changed. My dad would sometimes make a joke or two avout gays- but nothing serious and my mum disapproves completely. I really want to tell someone, but the rest of my family are SUPER RELIGIOUS! My aunt home schools her kids and teaches them bible stuff and my uncle used to be a tough criminal guy but now hes a pastor (ironic i know.) but anyway, is there any adive you could give? Im really confised atm and ive exams but cant focus and everytime i think about it i get all depressed:/ please help:) x