I imagine my girlfriend having sex with her dad?

I'm 21. I'm lesbian. When I have sex with my girlfriend I sometimes imagine her having sex or getting raped by her dad. She calls me daddy while we have sex. So I can't help but to not think the way I do. With my ex she told me she got raped by someone and I would imagine that. I know it's really messed up. I truly feel sick about it all. I don't want to tell my therapist because I don't feel comfortable with him at all. I honestly truly want to stop thinking of things like this. I feel like it's ruining my rs because I want to be truly focused on her and just her while we get intamate. But I also feel like she wants to have sex with her dad because when she talks about her real dad sometimes she'll call him daddy too. Honestly. I just feel like girls are truly not thinking of me while having sex so I feel like I have these thoughts out of anger towards them. I know it isn't normal but Id like too know everyone pov. Long story short about my childhood. I was neglected since I was 3 so I lived with neither father or mother. I have an extremely hard time trusting people. When I truly love someone one I truly don't believe they love me so I'll manipulate them and get off on thinking of them getting harmed. I also get turned on by girls in pain. I'm really fucked up. I'm unable to feel empathy. I don't understand others emotions. I simply don't care when I hurt them. I don't know what to do. I just need advice. If you're going to leave negative comments don't bother. I already feel like shit about myself and I just want to get this off my chest.