It's sad, because I generally can't get sexually excited unless I imagine being hurt or abused now. When my boyfriend has sex with me, I imagine I'm drugged and can't do anything or that he's related to me. It's fucked up, but I don't know how to stop it now. ((He knows about all this, but he's not into it)). Can you rewire that type of association?
Yes I think you can rewire that thinking.
Imagine the situation where once upon a time you derived a small amount of pleasure from a small taboo thought...
It felt good, and so you explored the taboo thought a little more...
Slowly the taboo gets deeper and your pleasure seems to keep increasing... to the point where it feels like the only way to get such intense pleasure is to indulge in such intense taboo thoughts.
With me so far?
Now imagine you could rewind, and discover a different 'little thought' that pleased you... perhaps something as simple as very sensual kissing, or massage etc...
You could, in time, spiral deeper and deeper into those thoughts and acts in a way that gave you more and more sexual pleasure right?
As things stand right now, you're getting your best kicks (or only kicks) from the very taboo thoughts, and possibly crave the taboo thoughts that give you fantastic feelings. But really, it's the fantastic feelings you crave right?
Putting aside the chemical dependency on drugs, it's similar to a drug addict who might be hooked on heroin. What he's actually addicted to is the feeling that heroin is giving him, but just assumes heroin in the only route to it. You're in that same situation. You've locked into the assumption that taboo / incest thoughts are the only route to intense sexual pleasure.
Rewind and try to discover just something that might give you only a little pleasure - then start 'spiralling' into that instead... eventually, you might be deriving incredible pleasure from the most sensual and intimate massages (or whatever floats your boat!). Only it'll be a hell of a lot healthier for your mind and soul than incest etc.
I think for most people there's one or two things that really gets them off... but that intensity evolved (just like yours did). You just have to back up and start evolving something a little healthier!