I cheated on my wife three years ago. She agreed to forgive me if we opened the marriage but now I live in agony every day

So basically my wife (39) found out that I (41) have been hooking up with a woman I met online who lived 2h away. When the woman visited we checked into a hotel. This went on for 3 months and we had met a handful of times when my wife caught us. she was waiting in the hotel lobby and saw us coming down from the room. She left me the next day.

We separated for 8 months and they were terrible on all of us especially the children (m9, f7 and f3). We started talking about getting back together. My wife thought that since our sexlife wasn’t enough for me, and that she was sure I will cheat on her again, we might as well open the marriage. I told her no because I’ve learned my mistake but she wouldn’t waver. I relented. We decided(she did) not to tell each other the when, where and with whom.

Now, over two years later, we are back to normal on the outside. On the inside I’m dying a little each day. Every time I see her happy I wonder if this is just her old bubbly self or if she was thinking of someone. She is a very beautiful woman and I’m sure she has no problems finding men who want her. Whenever she takes a shower after coming home, whenever she rejects my advances I think that she has been with someone and that kills me. I have tried to discuss closing the marriage again but she shuts these attempts very quickly with the divorce card. Before all this happened we had amazing sex several times week but now, we have probably done it 4-5 times these past 3 years. She demands I use protection and she refuses to let me eat her or make her cum in any way. I stopped asking because the sex is painfully bad now. I haven’t slept with anybody else because the look on my wife’s face in that lobby still makes me sick with guilt.

I don’t know how much more I can take. I love my wife and I want to spend the rest of my life with her. Will she ever stop punishing me? Have you ever forgiven a cheating spouse and stopped punishing them? What’s going on in her head?