IMHO everyone has "sick" fantasies. I feel this would only be sick if you would act on this fantasy.

Maybe the fantasy is based on the bigger picture of power play which is extremely popular. The fantasy of taking power away & using it. The fantasy of young vs old. I don't think you have to narrow it to one fantasy, but maybe it carries more significance than you think if you give it more space to expand & unfold.
Best of luck!
Again....just my opinion.

Edit
Hey it took a lot of guts to post this & talk about it!! Very brave of you. Thank you