My mom got on my iPad while I was at work and went through my Tumblr as well as my Twitter and found out I was bi. Now being the annoyingly Christian woman that she is, she gave me an hour long speech about how it was wrong and how "God gave me a ***** for a reason" and even said that I must think I'm part female since I want to be with guys. Then she took my iPad and still hasn't given it back (but I found it

)
But my question is why bother with getting upset over it? I'm 17 and leaving home in a year in a half so who I'm sleeping with is none of her business anyway. She keeps telling me that I'm bisexual because I don't feel loved and that it's all a lie and that I'm corrupted/damaged.
Edit: changed the question. Original wasn't what I was trying to ask exactly.