I think I'm going to try and displace responsibility as much as possible. Like "this wasn't anybody's or anything's fault, no one's to blame. This is my decision and I'm happy with it." I feel like going into detail on your reasoning is just going to fall on the deaf ears of people who have fundamentally different understandings of life and existence and will just see any logical arguments for suicide as proof that you were "sick" or whatever.
But you do you. Most people don't even leave a note whatsoever, so the fact you're leaving one at all is bound to help at least a bit with giving them closure.