Great question.
Here's my answer as a clinical psychologist (and ex-JW):
A well-trained and experienced therapist can teach relevant skills on how to effectively handle distress and regulate your emotions (instead of feeling overwhelmed and hypervigilant all the time), or help you process, better understand and resolve what you've been through, or teach practical, step-wise problem solving.
It depends on what you're immediate needs are and what the therapist offers. In my view, it helps if the therapist has some understanding of the harm caused by high control religious groups but if the therapist has been well trained - especially in the area of trauma - they will be able to help you.
On the other hand, I'd avoid like the plague therapists who simply offer counselling because while it may provide some (short term) relief to talk through your problems unless you learn strategies and new behaviours, "talking things through" is seldom effective in the long term for moving beyond traumatic experiences and finding a way to develop healthy life goals.