I worry that IF your wife has been cheating on you this entire time (which is highly likely based upon my experience), then you will likely regret giving her this letter.

If she's not cheating on you it's nice but I don't understand waiting until AFTER the divorce to state your feelings. Many people stop divorces the day and week of them becoming final. They get second thoughts and change their mind (or their affair partner dumps them). Give it to her today and you can get this letter off your desk and your mind sooner. You can release it along with her. Lest you rewrite it three or four more times between now and then.

Also...unless you actually cheated on her I'd have you remove the phrase "I was unfaithful and mentally divorced from you". You didn't and don't want to be divorced at all from her. That's why you came to DB, right? This phrase just strikes me as "you divorcing me is fine since I was unfaithful and divorced you mentally long ago". That's how your kids may read this someday too. I mean, there's owning your villagers and there's owning the village. I'd have you cut down that whole first paragraph immensely. Should you ever get the chance to express that verbally someday...then own your stuff more explicitly in person when you can add context; but this is in writing and could be used to say "see, it was your dad's fault...that's why I left you guys".

The internet is 90% complaining and entitlement and I hate it because I deserve better!