Anything will help

Every time i have sex with my girlfriend I am always thinking of ways to get her fingers in my ass. I've tried directly addressing my issue. she told me to fuck off then stormed out. I went through painful withdrawals from a heroine stint I went on for weeks after she left, but she returned to me and I instantly quit. she made me promise never to ask her of that sexual favor ever again. She then told me of a tragic experience she had when she accidentally killed a previous lover through acts kinky sexual perversion. She couldn't place the actual cause of death but her finger was certainly inside his butt hole when he died. So, naturally, she partly attributes the blame of his death on her self and her desires to finger anything stinky and warm. I respected her wishes, but sometimes she catches me with my own finger in my ass during our love making. we don't speak of those rare occurrences. I forget to take her past into consideration when I attempt to satiate my longing for perverse anal stimulation. I don't feel good about having to hide that desire though. I love this woman. I want it to work out, but speaking of this intense desire of mine seems to push her away. It's like I can even tell when she sees me thinking about it. She looks hurt, but braves the moment of contention between us because she and I both know that what we have is more important than a little finger in my ass. At least that's what all the couple-counselors have told us. But she can't go to anymore of those, we've tried so many and no one seems to be able to help. She cannot handle exposing her vulnerable past to any new ears any longer. So, I've thought to ask you for advice. see what I might be able to do that doesn't include her direct involvement or participation. Anything will help. Thank you.