Get out of a sleepover?

I have this friend that asks me to have a sleepover every single weekend, and I 80% of the time I don't want to go. Our moms know each other very well and plan our sleepovers without asking me first. I've told my mom to consult with me first but she just says "She's your friend and you don't want to make her sad, right?" My friend is really rude to me and invades my privacy, asks me if I'm "Gay" which insults me because I'm Bisexual. This friend also goes to church every Sunday at 7 am. I'm not religious, and have to listen to them ramble on about how Jesus is our savior and honestly I wake up at 6 am every morning for school, Weekends are my time to relax and do nothing lol. I can't ask my mom to cover for me or make up excuses or lies. I work hard in school and make A's and B's and just want to read or Skype friends at home during the weekend. This friend is also boring, she just uses her iPad the whole time and when I try and use my phone to text someone for a few minutes she says, "Can you get off that for once?" I go over to their house or they come to mine every weekend anyway, why is a sleepover needed? I feel uncomfortable sharing a bed with someone, I like my space. Anything I can say to my mother or friend to tell them that I don't want a sleepover every single weekend? Thanks. :)

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