What do you do when you cant stand one of your kids?

well i have an 11yr old son from a previous marriage. he has adhd and is taking medication, but i would say his adhd is mild to moderate, not really the whole problem. his father and i get along fine for the sake of our son, but i really don’t like him at all and have alot of resentment towards him. he moved out of state about a year ago. i have 2 other children with my current mate ages 1.6 and 3.2 and my 11yr old gets along fine with his step dad. the real issue is i feel the obvious dislike and annoyance i feel for him. my first reaction is to move away when he comes close to me and i can feel my immediate mood change soon as he gets home from school. I realize alot of this has happened over time due to his constant bouncing around and his inability to follow directions and his constant picking he does to his siblings. i always say with him comes the kaos. he does very well in school and also plays local sports, I’m doing the best that i can, but fear that my feelings are becoming obvious as it is getting harder and harder to hide. his step dad says i am to hard on him, but I’m very aware that the moment i let up he will do something to get into trouble. i have proven my point several times. i hate to say it but he proves me right every time. he just doesn’t think before he acts and i cant seem to give him positive reinforcement at all anymore. it’s like i give him a complement and take it away with a criticism all in the same breath. don’t get me wrong he’s a good kid, probably very much like all 11yr old boys, but i just have so much trouble being around him without being angry or just plain annoyed, it like i hear everything he does down to whistling all the way across the house and i cant help but yell at him to stop. please give me some advice on how to change my feelings for him, I’m afraid that they will break down his self esteem and cause him long term emotional problems. i mean if your own mother cant like you then who can right. and i know he can see the difference between him and his siblings, he understands that they are toddlers and require much more attention and patience, but soon it will become evident, i need to fix this before its to late.