Finding a place of peace is not running away. It is removing distractions so that you can find the answers within yourself that you need. I think your nervous system and heart would welcome it.
And I think if he is just showing signs of really beginning to look within, the truth talk is inadvisable. It took my husband 6-12 months of serious self-reflection to slowly, bit by bit, unravel his REAL reasons for the choices he made (that had little to do with me) and to grow the kind of emotional maturity that it requires to not get defensive when talking about how badly he'd let me and our daughter down. Before he could apologize with empathy without expectations of forgiveness. These are the changes that you need to see to have any hope. These are not skills or insights gained overnight. While emotional intelligence should have been learned in childhood/early adulthood, in my experience most people don't. Why your husband didn't do this soul searching after your first DD is... well, a good question to ask. But I think some quiet time away is what you need. If he goes off the rails - he's told you invaluable information - that nothing has changed. But more importantly, I think you are realizing that this 10 years of stress and anxiety and having to monitor another GROWN adult has taken you outside of yourself. You are more invested in his choices than in your own. In what is happening in his life, than your own. It's time to take back your power. You need to get out of his head - and in your own (which you are clearly trying to do.) Figure out who you are, what you want and IF he is a part of that. The answers may surprise you. And even if you do decide to leave - it does NOT invalidate the time you have been together. That time was real and valuable. But just because it was ONCE right, does not mean that it is still true today. The only person who gets to decide that is you.
BS - Female
Married 27 years, one adult child DD May 2016 “When we are no longer able to change a situation, we are challenged to change ourselves.” - V Frankl