OK. Very first lesson of step parenting**************....
You. Are. Not. The. Parent.
(and frankly, Stealth was pointing out a very confusing problem in your first post as to who you really are. How many step dads does your step son have?)
And before you get all upset at me, please note, I AM a step parent.
blending a family is not easy. Especially when folks don't get along. And well, if you were getting along you would not be here.
nothing in your posts suggests a reason to change the physical custody arrangments.
you have to realize that, what YOU want will never be more important than what your step sons FATHER wants.
You cannot compete with the father of your step child. You will NOT win.
You need to deal with the fact, that your wife, chose an ass to father her child. You cannot change that, but it will be a lot easier for you, if you accept it, and move on.
"It is easier to build strong children than repair broken men." Frederick Douglas