Wife Tells Me This After Forty Years Of Marriage

I never knew she was assaulted before we met, and not just groped by someone in passing, literally held over night and sexually assaulted for hours bound to a bed. She told me it was so tight that she could hardly move at all with ropes and duct tape securing her all over. The guy would play around with her tickling, then slapping parts of her then more sexual stimulation then back to tickling. One point she was pleading with him because she had to use the bathroom and it was going to be a mess if he did not let her, he bound her legs together and arms to her sides, carried her in there and sat her down on the toilet watching. She asked him to leave her in there, she would not try anything, he taped her mouth closed and fingered her anus until she started pooping. When she was done he put her in the shower and washed her off then back to the bed soaking wet was cold, went back to the sexual play and tickling her more. When he finally stimulated her enough for an orgasm he just kept going doing it non stop until she came many, many times and would tickle her at the same time which drove her crazy. He would give her massive amounts of pleasure then do something painful to bring her right back down from it like pinching her nipples or biting the lips of her pussy listening to her cry out in pain from it. She endured like six hours of this all night.
So like ten years into being married to her she asks me one night what my like bucket list sexual thing was, what did I want to do that I never wanted to ask her. I was happy with everything in our life including the sexual part of it, she was always very giving and loved to please for sure. She asks if I want to know hers and I say yes wondering what she would come up with because other than some anal play now and then what was left. She says she wants me to tie her up and do what I want to her, no limits and she cannot say no either and I am laying there thinking where did this come from because I was stunned a bit.
She told me at the time she just always wanted to try it, completely in someone else's control as she put it, wanted to be tickled, teased and anything was on the table but don't tell her my plan just do it. We discuss this a few times and one weekend evening with our kids at her mothers I am tying her with plenty of advice on making things tighter and more restrictive. I start playing around with her and she is very ticklish, she is making noises like she is mad about it but telling me to keep going and ignore her responses, she had an orgasm and I am thinking all is good now and start untying her, No! she says, keep going, do this for like two hours she says so I am doing my best and thinking what the hell am I unleashing here as she says harder, more of that yes, Oh my God as she is gritting her teeth but wants more.
When she was finally done I untied her and she cried some but told me that was amazing, she loved it, gave me her devil smile and said definitely want more of this so practice up on your sexual torture. I laughed but something inside me knew this was not just her mind having a fantasy but when I asked her about it back then she told me nothing, just wanted to do it.
Then came an evening about two years ago, we are at a friends house for a get together and they have a pool so it is always a great time. My wife as had a few to drink, leans over and asks me what I would think about Derek taking her home and playing around with her. I laughed asking her if this was another one her bucket items, married woman having a fling or something. Mind you she had a bit to drink and she looks at me and says she wants to be r**ed again, tells me it would be close enough and asks me to let her do it. I am like what the hell are you talking about? she says he barely knows us, let him take me home and do what he wants with me, promise I will never leave you just give me this.
I get her to the car and we go home, I had no idea where this was coming from but I was not about to just let someone take her home and she starts telling me all about what happened to her years ago. Now I am finally seeing why she wanted me to tie her up and play around with her but it was still not like reliving it because we were married and knew each other well.