How do I leave my wife?

I've been married for 11 years, my wife and I have one child together and we each have a child from a previous marriage, both of which are with us and not their other parent. Granted that they are older, one is going to start his junior year in college and the other starts her freshman year this fall. Then our child together is ten years old. My wife and have been through marriage counseling and things were better for a while, but to me we just don't get along. Things must always go my wife's ways and if they don't it's either a blow up or bitchy passive aggressive behavior. She consistently belittles and demeans my contributions to the family and consistently makes me feel completely inadequate. Her harsh behavior often leaves me feeling depressed and like a failure. There often been times where I feel like I have no way out at all. I feel like I do love her, but at what point is enough enough? Times are not always bad between us, but the good times are most certainly overshadowed by the bad. I just don't know if leaving is the answer, but at the same time I don't really want to go through the counseling again. Advice?