I have been reading your thread, and you are doing amazing despite such a drastic change in your ex. You seem to have acted wisely, and swiftly and you are going to come out of this OK. It's sad though. It's a huge loss. An elective death by your spouse.
I am truly under the opinion that if our spouses are capable of doing this once, whether in the name of depression or MLC they will do it again. There is something in them that just makes it ok for them to treat some one they were very close to in this way. Their perspective, the way they view life and relationships. It's just different. It's like trying to understand the opposite political party. It's two different brains acting and believing differently. I think we are at odds with ourselves when we are trying to appeal to them to come back. And that's why it often doesn't work.
You are right though. My ex and I never had a true partnership. He told me "nothing will change for you" when he left and he was right except I ended up with more money and more help with son. It took my son a week to even know his dad was gone. I am told by other people who saw what our relationship was like, how wonderful it will feel being in a real relationship with someone. I want to experience that with someone truly vested.
