Tantrums

I am at a loss. I have always struggled with keeping son under control and obeying me. He obeys his dad well but really pushes me. I tend to give in more being the softy and he completely takes advantage of it. So, when I try to reestablish parental control, I am faced with huge tantrums. And they are only getting worse as he gets older and bigger. So my question to other moms is, what do you do when your child completely and utterly won't obey? I mean they won't go to timeout, they won't go to their room and they certainly won't do the thing that you wanted them to do in the first place. Spankings don't work, taking toys away won't work. Today he actually hit and kicked me. That is really a first and I don't quite know what to do. I can still put him in his room but keeping him there takes everything I've got. He is so stubborn that he just cannot give in until he is so exhausted that he has no fight left in him. So in that sense I still "win". But like I said, he is only getting bigger and stronger.
If you have any suggestions, I would greatly appreciate it or just commiserate with me, that way I know I am not alone.
I really thought 5 would be easier. He better be super easy as a teenager.