Choking someone out

Is it normal to want to choke someone out. Years ago I lived in long beach for about a year. I was living with an L.A. County sheriff and we were completely in love and talking about marriage. But she introduced me to gaspers and loved for me to choke her right when she was going to cum. One night we went to far and I literally choked her out. I thought I had killed her, first thought I had was I just killed the woman I love more than anything. The second thought I had was cop killers who fall don't have a very pleasant stay in the system on there way to the syringe. Now she came back to me, and I ended up leaving the relationship because she wanted to keep pushing the limits. And wanted me to rape her, at that point it became to creepy. But now with my current girlfriend when ever she rides me I try and choke her out a bit. She never let's me but it turns me on beyond belief, did she fuck up my brain, or am I just a normal guy????