Although I do not believe that all the ex-members of cults need therapy, I admit that some of them need. However, ex-members of cults need to be aware that some therapists may harm them rather than help them. Unfortunately, such cases happen.
Before hiring a therapist, I would recommend ex-members of cults to read the book “Crazy” Therapies: What are They? Do They Work? by Margaret Singer and Janja Lalich. There is an abstract of this book on ICSA website: “Crazy” Therapies: What are They? Do They Work? The Therapeutic Relationship.