Sweet, no one has said that it's only you who has the issues, but you do seem to be making it hard for yourself.
I've read all your posts re your family issues, and judging from the posts, it does sound as if you dislike your SDS. You've called him a lazy so and so and also sounds like you resent the time he spends with his father. He is entitled to spend as much time as he needs with his dad, as you are entitled to spend time with your DH too.
And your DH wasn't far off the mark with the affair thing, granted it was a few months ago that he said it, but you haven't really proved him wrong by sneaking behind his back and meeting this guy and then kissing him.
I'm sorry if this sounds harsh but I felt it needed to be said.
Counselling certainly sounds like it will do you the world of good.
I hope things start to get better for you.
xxx