My boyfriend's ex swaps bodies with me and fucks him

I get a strange phone call from my boyfriend's ex, I think she is trying to tell me something... but suddenly I started to feel bad.What's going on? why don't i have control of my body?What is she trying to do with my body? Why is she seducing my boyfriend?I can't believe my boyfriend is having sex with her, Wait... does he know Sarah is the one controlling my body!?