What attracted you to this woman in the first place? Your ex wife had Borderline Narcissistic Personality? That tells you something about the type of people you are attracted to, need to work on that issue with a therapist to avoid issues in the future.I rarely know when she's happy or content. I ALWAYS know when she is angry, frustrated, upset, *fill in negative feeling here*. That is exhausting by itself. I have no problem listening and apologizing when I'm wrong or when I'm the reason for the negative feelings, but when they are almost constant, it makes me want to just stop.
How did you guys get together, were you both out of your prior marriages/divorced, etc?
Put your kids first (every time) it is good you are leaving her. Now get it together, get a lawyer, get alternative accommodation for your kids, sort out the finances and move on.
From what you are saying there may be signs of BPD if she is constantly not happy and harassing you?
How is her relationship with her own kids?
Blending families is not easy at all but if you are she are not getting on it will make it more difficult esp with teenage kids. Sounds like you guys rushed into this arrangement.