Should he spend so much time on the computer?
It appears that you have a major problem in terms of how your husband is treating your son's behavior. You and your spouse need to be on the same page about all these issues or else your son will be getting mixed messages and continue to play you and your husband against one another to get what he wants.
Place the computer in the family room or a place where everyone can see who's using it. Your son shouldn't be able to shut himself in his room to play on the computer for hours at a time. Unless your son is using the computer for academic purposes, limit his computer use to an hour a day. I would also suggest that the combined use of computer and TV time should be no more than an hour and a half each day.
As for his chores, I would sit down and draft a contract with him, posting a weekly list of chores in plain view. As he completes the chores, he needs to check them off. If he does not comply with this within the first week to ten days, then I would recommend that chores be assigned on a daily basis with consequences attached to non-performance.
Your son has been allowed too much power in your family. He seems to do whatever he pleases and shows disrespect toward you.
I hope that a different family therapist will provide you with a much healthier and more effective approach to parenting your son and encourage you and your husband to act as a team in the process.