Need advice for cuck

We got married pretty young, and looking back, the early years of our relationship were rough mostly because of me. I was a terrible partner back then. I was deep into different drugs, partying too much, and just not really there for her emotionally or in any real way. She spent her early 20s basically taking care of me, picking up the pieces when I was messed up, staying home instead of going out with friends, and missing out on all that carefree fun most girls her age were having. She sacrificed a lot for me, and I know I wasted some of the best years of her life. I still feel guilty about that.
Sexually, things were complicated too. Im not the biggest guy literally, my penis is pretty small. Shes thicker in all the right areas, with curves that drive me crazy, but the size difference became a real problem in our relationship later on. We talked about it openly because were pretty honest with each other. It bothered her at times, even if she didnt always say it harshly. One night I decided to do something about it. I took her to a sex shop and told her to pick out whatever she wanted. She was excited, browsing around, and she ended up grabbing a few things including this big BBC dildo. When we got to the register, the lady behind the counter and my wife both started smirking and chuckling a little as they rang it up. It was pretty embarrassing standing there, but honestly, it didnt bother me that much. If anything, it turned me on seeing her so into it.
The first couple times we used it, I could instantly tell how much she reacted to it. Her whole body responded differently louder, more intense, completely lost in it. I could see she was really into it, and weirdly, that made me happy. It turned into her using it almost every time we had sex. That opened the door to her getting into the cuckold thing. Ive always been very open in the bedroom, so when she started talking during sex about how much she liked me watching her use it, I went with it. And to be honest I did like watching. She loved it so much that she eventually told her sister about the toy and the dynamic. Later, her sister even bought her a bigger one as a joke birthday gift. It was wild, but I was actually happy for her. Our sex life got better because she was finally being satisfied in a way she hadnt been before.
My one real issue was the messiness. Since I go into work early, Id sometimes come home during lunch or after my shift and find her toys left out on the couch, in the bathroom, just lying around the apartment. A few times I had maintenance guys over to fix plumbing or whatever, and Id walk in and see one of her dildos in plain view. That bothered me. She was super understanding about it though, and she tried to be more careful after I brought it up.
Over time, she started enjoying her life more. Shed go out with her younger sister and friends, take vacations, have fun the kind of stuff she missed in her early 20s. I was genuinely happy to see that, even though I knew her sister could be a wild one, kind of a bad influence on people who are in relationships, if you know what I mean.
Then she brought up actually cuckolding me for real. Her sister had been pushing the idea, telling her to go have fun. At first it threw me off, but because of how much Id put her through early on, I eventually got more comfortable and open to it. She mentioned this guy at the gym who flirted with her innocently. I knew about him, and I even told her to flirt back a little. She was super into it. It escalated she ended up having sex with him and other stuff. I was okay with it at the time. She said it was no strings attached, just good sex. It became a recurring thing. He even came over for dinner sometimes, and she never told him that I knew, so it always felt a bit awkward for me.
Now Im looking for advice because things have gotten complicated. Her sister knows everything and has made sly jokes to me about it, which makes me uncomfortable. My wife gets mad at her for it, but I swear I sometimes see my wife smiling a little when it happens. Lately shes gotten really into black men almost fetishizing them and seeming infatuated. Thats made me uncomfortable too.
Just last month she went on vacation to Florida with her sister and friends. We talked beforehand and she set a rule that I couldnt ask any questions when she got back which was never part of our original arrangement. I was already upset. A day after she returned, I snooped on her phone and saw multiple videos of her giving oral to a guy in the hotel room. I confronted her. She was extremely sorry and said she understood that even this arrangement has rules. But now Im second guessing everything and almost regretting letting her have her fun. Im worried that if I tell her I want her to stop, she might just want a divorce. At the same time, I think Id be okay if she continued but only if she did it in a respectful way that honors our marriage and the rules we set. Im not sure if she ever really will.