If you are worried about your husband leaving you in a sexless marriage, just ask yourself. Do you think your husband could do better than you? If the answer is no, then he will not cheat, and you have nothing to worry about. If the answer is yes, just work on yourself until he can't do better, then your life will never be better.
To be clear, I write about how people grow from trauma as well as extremely extreme thoughts. I, in NO CASE CAUTION ABUSE WHATSOEVER! Empathy is the among the greatest gifts we possess!
Imagination is another of the greatest gifts we possess (quite akin to empathy) and I want to emphasize that imagination and reality can be two completely separate things.
Introspection and daring to be vulnerable again may seem impossible but temporary relief through sadism and abuse will only make you feel worst on the long run. No matter the intellectual pain you feel, passing it onto another being by force is the worst thing imaginable both for the victim and for yourself..... Now, if you know it's just imagination.... then.... PLEASE let your freak flag fly (being mindful of what some people might interpret)!!!