I feel your situation. My son was also very defiant from age 7 to now 14.
Many times I got so angry and so stressed as well. I yelled and he yelled back.
It was so unhealthy for my health. About 2 years ago it has gotten much much better. He listens more and has less angry outbursts.
We talk a lot about his school, what is going on in the world. I am so happy now.
I follows all ADHD advices such as good diet with plenty omega-3 supplement. Tried neurofeedback therapy also.
I don’t have a magic recipe for what happened but I think I had to become more patient and expect less of him.
That reduced the stress level. I involved with him after school by becoming an assistant soccer coach for his team.
I think that brought us closer. I think the key is to improve on one little thing at a time and not get frustrated by set backs.
Everything is not perfect. I still get frustrated and angry many times when he doesn’t seem to get it but we are at a point where we can talk with out yelling.
So please be patient. Work on yourself first. Try always to be gentle in your manner and hope that as the child grows up he will be more understanding of what the parents are trying to do.