I'm so sorry hun. As others have said, you didn't blow it. Stop blaming yourself for your W having an affair. See how silly it sounds when it's phrased like that? I had someone frame it the same way for me and it really made me pause. It was helpful.
There is no way to know that if you had acted differently if WW would have slowly left OP or not. We can sit here and speculate that it might have worked - it might have not worked - but you really don't know. What we do know is that A) you will be okay and B) none of this is your fault, and you've been carrying it for a very, very long time.
I think it's time to go back to focusing on KG and only KG. You can call it "going dark", you can call it a break-up - but whatever you call it, I think you need to really pause and stop being sucked in. She is taking all of your energy and it's not a fair exchange because you're not getting anything out of it.
You're in IC now, so maybe you can really focus on healing yourself. It's a trauma in a way, and healing is needed. Some folks call it "GAL", but there is so much more to it than that. It's not just go out and forget and stay busy - you have to do some sitting with the pain, acknowledging it, and releasing it. It takes time.
You are allowed to either be done with WW or to still hold out hope for a future. That's totally your call and either is valid. But if you're holding out hope remember that the time for this is not now. It's likely not 6 months from now. Really give her the space to make her other situation real. Remove yourself from it completely.
The cake-eating in this situation is one of the more intense I've seen. If you want to change the dynamic it has to be from you because I have no doubt she'll be back in touch with you if she hasn't already. You have the power to drive your own healing here.
