If being an RN is stressing you out so much that you can’t sleep (completely understandable because that’s an extremely emotionally and mentally taxing position) then your only options really are to find a different job as you did, or perhaps have regular therapy sessions to help you through it. With your training, you can definitely find less stressful positions such as a nurse educator, consulting, public health sector. Maybe you could ask your former colleagues with a bit more experience if they know of any position that would be less stressful for you.