it can be tough to change behavior that has been so long standing, as it has often become part of the child's self-concept (e.g. 'I'm the bad one'). You will have your work cut out for you, but the good news is that if you and your husband can work well as a team, you should be able to make some positive changes in a couple of weeks. I am glad to hear that he is not mean or aggressive, as that will make thing easier.
It sounds like you and your husband could use some help. I would seek a referral from your pediatrician to find a psychologist who has lots of experience working with parents in similar situations. The psychologist may recommend a formal assessment to rule-out ADHD or emotional problems (depression and anxiety can manifest as behavior problems). An assessment at his age can provide you with very helpful information before the upheaval of middle school really begins. While you are waiting to find a therapist, I strongly recommend you pick up two books: The Kazdin Method by Alan Kazdin and How to Talk so Kids will Listen and Listen so Kids will Talk by Adele Faber.
Whether or not you have psychological testing, therapy will be important. I would seek psychotherapy that includes lots of parent work to help you learn to manage his behavior in positive ways (you are so right about spanking, the research has shown for decades that it is a very ineffective way of changing behavior in any positive way). Find a therapist who can provide Parent Management Training, Parent Effectiveness Training or Parent guidance--all include learning to manage behavior) as well as individual therapy for your son. Boys this age often have trouble coping with anger, and your son can learn better ways of dealing with his emotions.
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