Mama, I am sorry, they all have their times, I think that is why they are so damn cute and funny, is like it is their defense mechanism, lol.
I am not there "yet" with my toddler, but I have a 13 year old too.
I don't remember exactly how she was at 3, but I can tell you that she is now a very smart, independent, polite, funny, well mannered, etc, etc, and I don't think I was the best mom ever or that she wasn't perfect all the time.
We had our times, and some really bad days, but they don't seem so bad now. Now our problems (no boyfriend, no facebook, no make up, etc, etc) seem so hard, harder then the tantrums when she was little, lol.
I am sure when she grows up I would look back and this will look no so bad then.
You keep teaching right from wrong, keep loving him, keep being clear with what is good and what is not, and things will soon move on....to the next wet of parenting troubles, lol.
Hang on there, this too should pass.