The letter doesn't come across as manning up. It comes across as whining.

I'm not familiar enough with your situation to offer a good suggestion of what manning up in your case would look like, but I know this isn't it.

I'm more sympathetic than I sound, I promise. Sending the letter is not in your best interests.

Me: 44
H: 44
Kids: 20, 16, 16, and 10
Together/Married: 22 years
H announced he was emotionally detached and considering D: 4/4/16
H announced he is going to try to stay and reconnect: 5/1/16