One of the best things you can do for yourself, your family, and your child is to get yourself some help. Here are some things that I've found useful. I hope they help you, too.
Russell A. Barkley, "Taking Charge of ADHD: The Complete, Authoritative Guide for Parents"
Ross Green, "The Explosive Child: A New Approach for Understanding and Parenting Easily Frustrated, 'Chronically Inflexible' Children"
Ross Green, "Lost at School: Why our Kids with Behavioural Challenges Are Falling through the Cracks and How We Can Help Them"