WOW such perfectionism and control issues in such a little guy! i was fascinated reading your post, honestly. but i really feel for you too.
know what i think? more playdates. LOTS more. sorry to say it lol. BUT i really honestly feel like this kid has been SO coddled, SO catered to, that nothing but a good old fashioned kick in the pants dose of reality is going to do it. he HAS to learn how to get along with someone besides his mom. really.
Honestly, it stinks for your kids. BUT i believe that 99% of the time, unless someone is bleeding or broken, they should be working things out themselves. how about taking them to the park? lots to do, and you don't have to sit and entertain. just a thought.
it just seems to me like, in the name of peace and making nice, you really bent over backwards to cater to this kid, just like he's used to. i would really love to get ahold of him lol. see what happens when he is expected to be in the real world.
i just said this in another 3 year old post - but i think 3 is not the ideal time for the "reasoning" and "talking it out" methods we have rammed down our throats these days. a 3 year old with complete control is SCARY. sometimes "because i said so" SHOULD be enough. really.
kids adapt to different expectations. the spoiled rotten brat at home suddenly performs great at school because his teachers actually discipline him. i bet with a little coaching and time from you he could actually enjoy his time with you. think how wonderful it would be for him to see what it's like to be a "normal" kid. probably idealistic of me....
goooooood luck!