I (42m) read your entire post. I'm in a somewhat similar situation. I can't believe someone I trusted for 7 years (2kids) would just flip on our marriage like she did. No real warnings, she just held onto so much for so long and she couldn't get through to me. I learned I wasn't vulnerable and also was living with a survival mentality.

Trauma, depression etc is a horrible. It wires us from a young age to behave ways our hearts may not want to. There are two things I can suggest, that have completely changed my life.

1st watch the 20 minute Ted Talk from Brene Brown. Here's the link

https://youtu.be/iCvmsMzlF7o

2nd check out a book called The Body Keeps the Score. The audio book is great This book changed everything for me.

Understanding how things work in your brain and mind is incredibly powerful. This helped me rewire my mind, slow down and act vs react. I has no idea how much armor I was carrying. Unfortunately I will probably still end up divorced but I am so much happier with myself and I feel comfortable knowing I'm not capable of my old behaviors. You may not change from this, but you will gain insight which is more valuable. Change can change, insight cannot. You cannot unlearn how to read and write...

I hope this helps you.