Parent in crisis

I am in the midst of parental crisis, I alternately want to pull my hair out and scream, or break down and cry. I'm just not sure what to do with O lately, everything seems to be a battle with him, from dinner to homework, to how he talks to and treats his brother and J and I, to how he talks about himself. I have reached a point where I question what I can/should be doing as a his father, because things shouldn't be this hard. On J's recommendation, we've started reading a parenting book. Nothing makes you feel like a shitty parent more than one of those. Basically it makes you feel like you have permanently scarred the little darlings with how wrong you have been doing things, and that they most assuredly will be meth addicts robbing liquor stores by their teens. Have I really been doing things so wrong all this time? Is it too late to fix? Have I raised the two boys differently, because they sure act differently. You start to go through every interaction you've ever had with your children, wondering where it all went wrong. I'm trying to implement ideas from the book, although perhaps I should read more than a third of it before I do. For some reason my attempts don't go the way the book says they should. I try not to be too hard on myself, because I know some of it is a function of O's personality. I also wonder what did I do so different with Q that he behaves differently, or perhaps he'll end up there too in three years. I almost feel like I have a teenager in an eight year old body, and I fear for what our dealings will be like when he actually hits that age and we have the added bonus of dealing with raging hormones. I wonder if a lot of it isn't just a desire for attention. It gets hard when you try to talk him about something he's done and he turns dramatic and starts in with his new favorite sayings, "I know, I'm such a jerk!", or "I'm just an idiot!", neither of which has ever been told to him or even insinuated. But, it gets the desired response of us telling him how wonderful he is. My biggest challenge lately is remaining calm when he tells me, "you'll regret this!", followed by some sort of threat. Unfortunately that probably comes as a response to how we have dealt with him, making threats to take away tv/computer/video game time, unless something was either stopped or accomplished. Trying very hard not to do that now, as my father taught me, never make a threat you don't intend to keep. As per the parenting book, we're trying to empower him, by giving him choices, thereby he learns to be responsible and doesn't have something t rebel against. That works great, till you give him a choice and he says "neither, what do you think I am an idiot?!" I better go read more of the book, to find what I answer to that.