What is the period of iddah after Khula?

What would be the period of Iddah for a women who took Khula after 4 years of separation from her husband in her 7 years of married life. Within these 7 years she lived 3 years with her husband and 4 years with her parents, as her husband and in-laws were causing mental harassment to her. She has a child and the husband after Khula, has clearly rejected to give maintenance for her and for the child.