I know your exhaustion. My son is very similiar. It seems he must always have the last word in every discussion where he is getting "no" message from me. I found the book "the explosive child" by Ross Green to be very very helpful.

Ross Green's approach to explaining and more importantly coming up with strategies to help were a very big help for us.

One important lesson I learned is that when a person/child is in the moment of breaking down ... it is already too late to reach that person because their mental/emotional IQ has already dropped 30 plus points. You might as well be yelling at the wall. So, the trick is to get to them BEFORE hand. which is a trick. For my son, he struggles to recognize that he must relate differently to his parents than with teacher than with kids his age then with strangers .. ect. That is what Dr. Mel Levine (another great author) explains as code switching. Some kids don't know how to code switch and so they behave as if they do not understand the authority or pecking order for kids.

For me, I take moments of calm and talk to my son. I say something like, you know... when a child your age starts coming up with reasons why they should be able to eat the entire bag of cookies after being told no ... It is not OK. It is not expected for a child your age to keep coming up with logical reasons as if the child had the same level of power as the adult. And so, no matter how much you might think that your logic will be appreciated and wanted .. it is not. You should simply reply "ok mom". And then when the moment comes and my son is being told NO.. and he starts up .. I calmly prompt him .. just say OK Mom. And that seems to put a bit of cool water on the heater enough so that we can talk about it more calmly.

During moments of calm I also talk to my son about the fact that sometimes you can't discuss a disagreement in the moment and that it might have to wait until later. And so when the moment arrives and he is being told NO, and if that moment means that we are not in a position to discuss.. I tell him that also. I say, just say OK Mom. And I say, there isn't time to discuss right now, how about we talk this evening before bed. And then, of course, make sure you keep that before bed time to discuss.

The explosive child (ross green) and A Mind at a time (mel levine) were very helpful for us to take the emotional sting and turmoil out of dealing with my son when he gets the NO reply.

Hang in there, it is not fun but can turn out ok. My son is now 11 and he is doing great. We started working with him when he was 4 years old and it has a rollar coaster ride at times but always going in the right direction. So I can tell you that smart mouthed, very high IQ little boys can be coaxed into civial behavior so that they can grow to young men who will make their way in the world successfully. I didn't think this about my son during the early years. I was sure that he would end up in jail or permanent detention from his constant talk back and explosive behavior after not getting his way.

So hang in there and keep looking for what works for your family. Don't give up. Don't pull away from your son - he needs you. And he is not happy either right now, he just doesn't know why and doesn't know what to do. He has all the intelligence but not the wisdom/know how to navigate the world. But you can help him get there.

Sorry this is so long. Just wanted to encourage you to keep looking for solutions because your son is only 8 years old - there is still lots of time to make a difference for him.

Good luck