She is scared. Her little world is tumbling around her and she can't understand it at all. Her mummy and daddy, the most important people in her life are always angry, at each other and at her.
So, to correct the situation and abolish the fear is your main objective. Self control, no more stress and bickering, it isn't going to solve any problems in any case, and lots of quiet reassurance. You will have to be very, very patient, and tell her the same things over and over again until she really feels they are second nature. You need to get out of the house (as a family) as often as you can, it needn't cost any money, just go for a walk or go to the park and play with her on the swings.
Be gentle with her, she needs you so much at the moment, she is only just past being a baby and the world is big and frightening. I don't think it is a good thing to leave her crying, I would tend to stay with her until she settles, just gentling her into sleep. Once she feels more secure you can leave her awake with a book or a toy, but for now I think you will have to just be patient and sit quietly with her.