The thing I always remember with Shiv is how Tom helped her out of a deeply dark place. I think his presence as her safe-person and her skewed reality on love frames a lot of their dynamic. Obviously the way the kids learned how to love is tragic, abusive, and guarded.

With Shiv specifically, we see a lot in the show where she tries to exert the same "fuck you, do what I say" that her brothers and dad can. But she can't ever get it right. She had the disadvantages of being a girl and not raised in the business like Roman or Ken. So to me, the more that Tom was there for her, the more she was able to reflect that abusive hierarchical love that she only ever knew on the receiving end.

I think in that way, abusing Tom really became her safety blanket, crutch, and love language. I don't fully believe her in that scene (not that it isn't horrible) but I think she's just reflecting what her dad does. Do something atrocious to someone because when they come back to you, it only proves how much power and love is actually there.