Congrats on nursing so long!
The answers are in your letter! paragraph 3-you don't like dealing with his unhappiness (tantrums i assume) if you don't nurse him. It is hard to resist knowing he loves something, but reacting to his anger and tantrums isn't good for him, he is training and trampling you and will not respect you if you aren't in charge as his protector-basic truth.
paragraph 3: You haven't established the schedule of 2 times a day if he is permitted to do this and is keeping you in the house. He can't go back to nursing a few times a day on his own, without your breasts.
paragraph 4: You'v established he drinks other things-it's not about thirst, it's about comfort, and not knowing how to sooth his own boredom anger frustration etc.-thus the tantrums.
paragasph 5: His dad does not perpetuate the behavior by being gone. NO EXCUSES! Many dads are gone all the time working (mine for example is gone months at a time). You are his primary teacher and caregiver-even though dad is #1 role model. But he should back up all your established rules when he's home.
paragraph 6: You shouldn't act based on dreading his tantrums, you should discipline him not to have tantrums. He's not suffering, you are. No, actually he is suffering too with tantrums, so you should not allow them and he'll be much happier.
paragraph 7: For him to react in a self destructive angry manner because you breasts hurt and you can't nurse all day?? Momma, sweetie, you do know better. This is not a good lesson for a boy this age to learn. You are not helping him, you're hurting him. Throwing things like pacifiers or anything else angrily should not be allowed and should have a consequence.
paragraph 8: He is intelligent motivated, happy, behaves well with others....all the tools to improve in his wrong behavior which you have enabled. No child can control themselves from having tantrums (thus the "normal" stigma). It is your job to teach him not to have them by enforcing discipline. He wants to be a good boy and is a good boy. Enforce this behavior.
OK! All easier said than done, but don't feel that you are being nice to him by letting him control you. When he learns he controls you, he loses security in your strength and in himself. Tantrums should not be allowed. Enforce discipline for the tantrums. As for the nursing, find positive fun ways to STOP nursing him. Keep your shirt on, literally, do fun things, and when he throws fits, discipline him. NEVER REWARD TANTRUMS WITH BOOBS!!!
Yes, he will rebel after being in charge for so long, but he will be better off when he learns to redirect his energy in positive ways. You can also wait until later, but you'll miss the chance to teach this lesson, and it will be harder. You'll have a much better relationship and more time for fun when this stops acting this way. You obviously love your son very much and want to make him happy. You have done a wonderful thing nursing so long. He wants to make you happy too, it's your job to teach him how to be a gentleman.