optimismandlove

Optimism IS a wonderful state of being. I agree.
I can relate to a lot of what you said. 3 years ago, when our relationship started, I was briefly told my pwBPD had BPD. I didn't look into it, so I didn't understand it. There have been a lot of ups and downs since then - most I didn't understand until I recently found out what BPD is and why it affects so much of our relationship.
When I first started reading about it and then confronted my partner (and I have to say I CONFRONTED and I did not handle that well at all) I was met with what I call the black wall of hate (when he shuts off completely and then acts out self-destructively, in this case he dumped me and started looking for a new GF).
I did what you did, I let him hit rock bottom, then allowed him to open up about what he'd been through. It did open my eyes to a better understanding of his early life; and, for him, he feels like it's the first time he can trust someone to be able to talk about it.
When they open up, it does give us the opportunity to approach it from a different angle - that which we understand is easier to face and deal with. There are two people in this (they may not always recognise that), two people struggling to understand "why" (we often forget they don't understand why they do the things they do), and two people in a place of hurt trying to get better.
You and I are in the same place - our SOs have acknowledged the need for and are willing to try therapy.
My pwBPD may take ten steps back to be able to take three steps forward... .
Yours may too... . but it sounds like he's willing to try so that is a positive ++

It's not easy to be in this, but lately I've adopted the AA approach "one day at a time", and acknowledging the rays of sunshine after a long hurricane season... . More storms may come, but I'll worry about them when they get here... .
I'm optimistic and I hope you remain so too... .
Please do keep us posted