******************* Hi Stolen Future - welcome to the Midlife Forum!
I saw your email, and have not had a chance to respond to it yet - but I will.
You cannot typically wait it out - and have things return to normal.
Normal is (most likely) gone - and a new "normal" is what you will need to adjust to.
The weekend my ex announced his "midlife crisis", which later turned out to equate to an affair, was the weekend my daughter brought her boyfriend to meet us for the first time.
I was a mess, knowing a divorce was impending, trying to cover and yet she was the one who broke it to him what was going on, by asking what he wanted out of the marraige.
Ostensibly, he has helped save other members of the community (the team) from making the same mistake.
To very briefly answer your question, "how long does the midlife crisis, first fling out of the marriage, usually last?
" - there is no "usual" anything in your situation.
The listing is quite long and I don't want to take time and make a "Sticky" out of the whole lot, so if anyone has a question about theirs, send me a PM with the first 2 or 3 serial numbers and I'll look it up for you.
This listing even includes those made by Remington, Ithaca, Singer, H&R, etc.