I'd agree that your experience sounds very much like SIPE (swimming induced pulmonary edema). It's very real. It's very scary. And there's no pushig through it, that's for sure.
I think you said it best when you touched on the aspects of there being no joy in your training and that you missed your buddies and your Sweatpea. It's the reason why after 4 IM finishes, I don't have any intentions of doing another one soon. I still love triathlon and I'm still coaching, but I don't want to push myself that hard anymore. I don't want to put in 20 training hours a week and I don't want to try to juggle 3 disciplines. And that's just fine.
So good on you for making a tough choice. One that goes against the grain of what our society tends to encourage, this rediculous idea that letting go of an athletic goal is in some way a failure. Good for you for chosing to have balance and happiness in life.

