I would be beyond livid if my partner not only discussed our private life on a public message board full of strangers but also posted a letter I wrote for her eyes only for thousands of people to read. Everybody here is defending the OP but frankly, my sympathy lies with the wife. Her private business is sitting here on a public message board and that is incredibly wrong. Though I haven't read the OP's previous posts about his wife, I can tell by the comments on this thread that he has had more than one *****fest about her. The bottom line; nobody here has heard HER side yet so many of you are making a lot of judgments about her while overlooking the fact that the OP is really OUT OF LINE. You are NOT helping this marriage by telling him how right he is and how wrong she is. How would any of you ladies feel if your husband called your child an immature brat and then got on a public message board and SLAMMED you all over the place and sat back and allowed tons of other people to slam you? How would you feel if a letter wrote in confidence was published in the friggin' Internet? I know I'm not going to change anybody's mind, but I have no problem at all standing alone and saying to the OP that he is being a JERK and needs to act his age and stop pointing so many fingers at other people. If you don't love her, divorce her, but for God's sake keep your private business between you, her and a marriage counselor.
As far as your wife saying she doesn't want more kids because of the way you handle her son; my God, I agree with her! Considering your marital problems it is selfish and ignorant to even consider bringing a child into this rapidly crashing marriage.