First of all, I'm sorry. I know you were somewhat expecting his decision - but it is still a gut punch to see it in black and white.
Is he in the replay phase of MLC? Or is this just the most ennobling sounding justification he can convince himself of? Either way - it's really a way of seeking something external to make him happy.
There are men who start families late in life and do well. However, I suspect they are ones who have thoroughly done with youthful living and are content as opposed to ones who are looking for a "redo".
It sounds very much like he is still working through his problems. It's tough but do your best to focus on your new job and the many wonderful parts of your life.
And yes - a brief reply that deals primarily with practical matters would probably be best.
