Why are you asking? It seems like you are looking for justification for a decision you have already made, but are afraid to take action on.
I also suggest therapy for yourself. Frustration, anger, are warranted. Dealing with them in a healthy way is necessary. You are in a legal relationship with her for the next 13 years because of your children.
Be kind to your children and make peace. With yourself. And then keep contact with her civil.