Yesterday, 06:59 PM
Wow, that is persistance! If he exhibits that same determination throughout his life, he'll go far. Maybe that's cold comfort right now, but still, wow!
It sounds like the issue isn't nursing per se, but rather his attachment to the breast. He's using it the way other kids use a blanket or a stuffed toy- as a source of comfort during his most stressful moments. I would try taking him to the store and letting him choose a stuffed toy or blanket, no limit on price or theme, with the stated intention that the item he chooses will be his comfort item (or lovey or whatever term you want to use) when he's upset. Then when a tantrum hits, have him go and get said item. You could also try allowing him to come in for cuddles, but interspersing some item, like a pillow, in between him and the breast.
One of my friends swears by the glitter bottle- see http://www.instructables.com/id/Calm-Bottle-aka-Glitter-Jar/. When a tantrum strikes, the bottle gets a good shake, and then the kid has to wait for the glitter to settle before negotiations for whatever it is he wanted are resumed. By the time the glitter settles, the unreasonable urge has usually passed.