You two need to not see each other for some time.

I'm starting to feel for That Guy because at least he can remain calm when POSTING ON AN ONLINE FORUM.

Mindscho, your hostility is actually seeping through my monitor at this point and making me uncomfortable. I understand that you're upset but grown-ups are supposed to know how to communicate with words not flashes of emotional heat. There is simply no choice but at this point to take a vacation away from each other and cool down.

This does not have to be an angry climax in your lives, so I suggest you plan a date a week from now to talk and discuss what is best for the innocent part of your unstable triangle (the kid.) Perhaps at that point you will both have a better idea of what is not working in your relationship and how to go about solving it.