Well, unless there are other men at that baby shower, I don't recommend that you go. That is, unless you like sandwiches with no crusts, iced tea, and oohing and ahhing over baby blankets, strollers and teddy bears. I hate those things, and I'm a mother.
Personally, I don't see anything wrong with you standing up for the marriage and telling her that she was wrong. And it sounds like maybe she cooled down enough to hear at least part of what you said. Listening is a skill. You are right when you describe the argument as anger, raw emotion, and moving mouths. In the future, say your peace as calmly as you can, listen to her side and then go take the walk. Don't let it go on too long.
I think I mentioned Retrouvaille to you before. If she is interested in working on the marriage, that is the way to go. They will lead you through it. You do all the work, but it is like Hansel and Gretel following a path of crumbs through the forest. Without someone to guide you, working on the marriage by yourselves is just a minefield. My H and I thought we could do it, and then we had an argument that was a public embarrassment. That's when we realized that we were really in the crapper and needed help. And we booked our Retrouvaille weekend. We have literally been happy ever since.
