Not Happy!

Me and my husband have been together over 12 yrs, and are expecting our 2nd child in about a month. Our first together is 6, and prior to having our son my husband cheated on me and had a son he is 7 exactly 9 months older than our son together. We have struggled so hard to get over the obstacles that we've been through together, after several breakups, and makeups we decided at this point we were ready to grow up and leave the past in the past. We've been married exactly one year. The thing is I am starting to dislike my stepson, he is a very annoying child, and is the complete opposite from how I am raising my son to be. My husband kinda knows how I feel, and I feel bad because he's a child but I wish I could go into detail all the reasons why I feel the way I do. It's getting so bad I don't even like him around, and I feel it's gonna tear us apart. What I thought I could handle as my life I'm starting to hate. Not to mention again we have our first daughter on the way. I'm so confused. 😪😢