What's wrong with me ?!🤔😱😫

So tonight my husband and I were having sex. I'll get straight to the point. He was eating me out and right away I began to imagine things. Him of course no other male, but here's the twist. I began imagining his ex wife 😱. Not really sure where that thought came from, but I couldn't shake the thought. I pictured him having sex with her and me. I pictured it the whole time he was down there. It made me squirt faster than I normally do. I didn't tell him at all. I'm not bisexual and I don't think that's what I want. And I'm not pregnant. I know some people have thoughts while pregnant I've been pregnant before but haven't imagined this extreme. Can someone help me figure this one out. I'm so not going to tell him. By the way she's remarried we talk here and there because my husband and her do share a child together. She's a cool chick but why am I picturing her with her ex husband who is my husband. 

THIS IS A SERIOUS QUESTION, SO NO JUDGEMENTS!!!