Why does this get me off?

Last night was one of the most intense and enjoyable evenings of kink I've ever spent with Miss H. On the surface it wasn't anything overly crazy or risky. It was just me dressed and the two of us laying under the covers together. For literally hours she had me alternately dry humping her leg or writhing in ecstasy as she stroked me over and over again, the whole time slowly and deliberately telling me in detail how much of a whore I was and what she planned to do to me in the future.

While I always go nuts when she talks dirty to me, last night it was at a whole new level. Venturing ever deeper in areas we've talked about before. Things like extreme cuckolding, forced bi, and numerous other things that were causing me to leak like a fire hose. The more she whispered her ideas into my ear, the more I groaned for her touch. I was both hyper excited and turned on while at the same time frustrated beyond all belief. Yet somehow the two opposite feelings were both so intense that they soon started to meld into one wave of pure sexual lust. Every word got me harder, every sensation, that much closer to almost cumming.
It was a beautiful state of being, an extended period of desire and pleasure that felt so much better than the fleeting joy of an orgasm.

I honestly think I enjoy the buildup and hold of extended tease and denial then the sudden release and loss of sexual desire from an orgasm. I still want to cum, but now it's more because I want to clear my head for a bit and take a break from the all consuming sexual drive and frustration of chastity then to get the brief high of cumming.

Anyway, as I was saying before, Miss H was going hard and heavy on the dirty talk and verbal abuse. At one point she made me orally service her while she masturbated herself. As she neared her orgasm she said "tell me what you are". That's her signal for me to begin degrading myself in front of her. To provide that little extra "oomph" to push her over the edge and come to a screaming orgasm. "I'm your little sissy bitch Mistress, your fucking whore. Your cross dressing cum licker", I grunted as two of my fingers rammed in and out of her. She groaned and with a yell reached a quaking orgasm.

She caught her breath and a few moments later as I pulled myself up next to her she sat up. "Wow, that was the first time in a while I had an orgasm strictly from what was going on physically. Usually I have a fantasy or something going through my mind but this time it was purely from what I was feeling. That was pretty cool", she said. Her tone was much different now, not the hard, domineering voice of earlier when she was calling me a useless little sissy, but her more typical day to day tone. This wasn't a comment she made with the explicit purpose of degrading me like before, it was just a matter of fact statement. Like we were discussing where to go for dinner or something.

At first it really hurt to hear her say that. It hurt to hear the woman you love say she has to think about other things to get off. I might dress like a slut but there is still a part of my manly pride that wants to hear that I satisfy her sexually. I was going to say something to her about it but then I noticed my own body had betrayed me. That previously soft cock was now rock hard and dripping once more. As much as I wanted to deny it, the evidence was readily apparent and pulsing in front of me. I loved the feeling of humiliation and shame that I felt when she said that. It's hard to explain why, but the more I'm degraded, humiliated, and dehumanized by her, the more I get turned on sexually and want to be with her.

The sting of her words, even though they were unintentional, was like electricity flowing through me. The fact that they were pure and honest, and not something just said in the heat of fantasy only made it that much worse/better.