Well Dragon's Muse ....
If you have the time and inclination you can certainly salvage it for the original piece or set it off on its own course. It is a very nice descriptive bit. It does seem to move along rather quickly but you might easily change the pace. (you are the author you know)
A couple of points. Your female lead (slut) is well described; her thoughts feelings and emotional responses ring true. A bit of motivational background might help but that may have been explored earlier in the piece.
Your male lead (Rat Bastard, Sir) is a little bit more problematic. His emotional response, his motivation, his thoughts and feelings aren't quite as richly described. While it isn't an interaction between equals, it is a scene between two very necessary parts so a balance needs to be maintained on a number of levels. Developing a descriptive back and forth between the characters will give the story a natural rhythm that will pull the reader along.
Pick out a few parts of the scene, (those that you really want to hold onto) when you describe his physical action follow it up with her physical reaction. When you speak of her emotional needs they should be balanced with his emotional response as well, the joy of power, the desire for unquestioned control, and add a little depth, he can show his love, gratitude, and devotion for her deliberate (wanton) surrender. The best sadist know how and when to be kind. It will make him as full a character as she is.
You need not run through the entire scene at once. Spread it out a bit, break her in slowly, take your time.
One word substitution,
You know how words have meanings and connotations, you’re using gash quite a bit for pussy/cunt/vagina. That’s a fine word and the connotation would run toward “wound” which is appropriate in this context. A gash would be more along the lines of a rough tear so you might also consider an occasional use of slit, also a wound but the connotation would be a more slick and slippery wet wound. Mixing the two up might be a little more powerful.
I’d be happy to e-mail you a more detailed critique if you wish.
Mad