Hello...my friend. Parenting is a learning experience. Unfortunately, our children do not come with directions. It is alright to make mistakes. I get a sense that you are being too hard on yourself and blaming yourself for the way your son has behaves.
Tomorrow is a new day...a new beginning. When you discipline your son, the main goal is to teach him rather than to punish him.. When you request that he do something, have him repeat your requests to make sure that he clearly understands what is being asked. If he gets an attitude, you must use an authoritative voice and tell him that his behavior is not acceptable. Additionally, you may need to watch him begin the task that you have requested and keep checking on him until completed.
Do not feed into his unhappiness and dissatisfaction when he is being disciplined. The more attention that you give to his negative behavior, the more he will exhibit such unwarranted behavior. When he acts out physically or gets that attitude, make sure that he is not hurting himself or others and then ignore him. He will cease his actions if he does not have an audience.
Try focusing more on his positive behavior at home. Really praise him when he is doing the "right things."
If things do not seem to be getting better and you are still at your wit's end, ask your son what really makes him happy at home and what things make him sad. Your goal in this exercise is to enable your son to open up to you and express his inner feelings. If he cannot verbally express himself, have him draw a picture of his family. Then have him talk about each member. You may discover that your son has been acting out in the manner in which he does because he misses the relationship with his dad. If your husband works 90 hours a week, is there enough quality time left over to dedicate to your son?
I hope these suggestions have provided you with a sense of direction and a clearer understanding of what may be happening.