You got Amy and Jack on your side. Jack noted Amy's current name tag doesn't reflect her history of posts or people she has helped. Nor can you guess her experience with the "other side". (Wasn't sure about the new name Amy but glad to see you helping. Hope your situation is good and growing.) Jack knows the other side up close and does a great job of nailing things down.
Take deep breaths, hang on, and get comfortable with the roller coaster from Hel!. You will leave here better than you arrived but how well is up to you, not the MLCer.
One thing a lot of people think they did wrong was poor communication with the partner. Ok, that is often true. It is often true with a lot of partners that aren't MLC or divided.
You're doing a lot of things right already. The gym. You eat. You rest. Your son. What do you read? Thinking about improving communication style can only help in the future. Mars ~ Venus books hold the attention and entertain as communication between the sexes is explored. Other people might list other good reads.
There's an out of print book by Peter O'Conner - "Understanding the Mid-Life Crisis"(sometimes at Amazon). It's less amusing than Mars-Venus stuff but shows you her MLC journey began in formative years.
The Four Agreements by Don Miguel Ruiz is almost pocket sized and great for people just seeking growth. Jack has suggested people also read stuff unrelated to your problem. A good idea.
Reading is just something that many explore In The Mean Time. That's where you are. "In The Meantime – Finding yourself and the love you want" – by Vanzant can be a painful read. Not cuz it's technical, but because it tells the reader in a life crisis to "just go for it!" This is what some therapists would tell your lady to do. It's the only way for her to confront her stuff once and for all. Coaching her into avoiding it will only delay MLC and bring it back later, bigger, meaner, and stronger.
You weren't going to avoid this for her. You couldn't. She couldn't. She may not survive it. You will. It has been chasing her a long time. The most important thing is that you learn to avoid being the path of destruction.
You didn't mention her dad. We can usually speculate within inches, but tell us more.
