first, sorry about what you went through as a kid. you definitely had some tough stuff to deal with.
second - i don't claim to have the definitive answer for you. from what you said, i understand that your dreams used to be a reflection of what really happened - including the important fact that it was unwanted, but recently they have become distorted with the implication that since you seemed willing, eager and active in the new dreams - you must have also felt that way back then when it happened - or worse - that you want it that way now.
let me offer another interpretation - you also said that at the time it happened you did find pleasure in the orgasm. i think what your dream is showing is that confusion of something "unwanted" conflicting with the fact that it was also something that gave "pleasure." that is a difficult place to be - feeling like the rope in a tug of war. i have been there - and still visit from time to time.
third - you didn't say if you have seen a therapist or have the opportunity to do that. or how long you have been dealing with the CSA issues. to me it sounds like what i was going through when if first opened the lid of pandora's box and started facing my issues. EVERYTHING became sexualized. i had repressed it all for so long that it came back to bite me with a vengeance. it was confusing and disturbing. but it didn't necessarily mean anything more than that i was feeling lots of stuff very intensely and was mixed up from the assault - like you say - consumed. maybe that is what is going on for you?
fourth - i've often wished i could turn back the clock to before i started this long and bumpy road of recovery. but when i think back honestly on what it was like then - it wasn't really better - just familiar. i believe you will find your way out the other side and it will be better.
We are often troubled, but not crushed;
sometimes in doubt, but never in despair;
there are many enemies, but we are never without a friend;
and though badly hurt at times, we are not destroyed.
- Paul, II Cor 4:8-9