Am I horrible? Sorry long story..

If I'm alone in this tell me so I will know I'm wrong and need to change or give up...

I'm about to marry my fiance. We've been together 3 years. I've help raise his son who's about to be 6 and we have a 2yo daughter together. I love my family very much, however I don't really like my stepson. Before I came along, he was beyond spoiled by his mother, father, and maternal grandmother. They did everything for him and let him have what he wanted. He didn't pick up after himself, didn't eat what he didn't want, and still to this day expects a toy or game whenever we leave the house. After he came to live with us permanently 2 yes ago, I've taught him to tie his shoes, clean up his room, eat what I cook and not a different meal completely. His father thinks I'm too hard on him but even my 2yo knows to put her dirty clothes in the dirty basket! My step son cries at every little thing and I can't stand it. Am I wrong? Am I too hard on him? They say I treat him and my daughter differently, like I love her more but am I wrong if I do?