Limerickence (I hope I spelled that right), I think you're doing your best to avoid any real negative feelings, especially anger or grief or sense of betrayal, you probably do have in your wife. For your wife to be screwing around literally in your house, on her birthday, that I would guess you arranged for her, telling you to leave your own bedroom because she wants to have sex with someone else....and you are still associating with these people, whom I understand are STILL married and probably the OBS' don't know about this shenanigans, I think you are deeply deeply not in love with your wife or in limerance.....I think you are just in denial. I think you have such a desperate need to cling to or hold on to this woman, and she sounds pretty awful to me, very disrespectful to you, and you just sound like a masochist who is willing to accept and try to find reasons or excuses for this abominable treatment of you. She might well be a mental case or alcoholic, I don't know, but she is NOT A NICE PERSON. And she is NOT respectful of you, which is a basic requirement for a spouse.
I think you need to stop wondering about her...I'm just gonna say flat out that i think she's just a bitch but you are afraid of losing her or perhaps being on your own. This is why I ask you to think about not what you want with her, but what you want out of life and specifically a relationship - in general, what your needs and goals are without factoring her specifically in. Once you have some idea of that, then maybe you can consider how this relationship fits in, but I think you are in severe denial about what she is like, what she did, how you feel about this, and what the future will be like. How can you want to continue in a relationship with someone who does only what she wants unilaterally and shows NO RESPECT FOR YOU?
This is what I see and I think you might actively consider at least some of this instead of just burrowing in.
I'm sorry if I seem harsh but I'm trying to shake you up because you seem like you're sleep walking through this relationship and maybe through life.