I'm new to the forum so, hoping I'm doing this right.
This is the letter I would write.
Dear Parents,
It is with great regret that I must inform you that as of (date), I will no longer be able to care for your child. I am currently experiencing personal health issues that leave me struggling to look after your child the way I feel s/he deserves.
I would like you to know that I have really enjoyed my time with your child, s/he has been a wonderful addition to our group. Please be assured that this decision is not personal, but rather, I feel it is necessary given my own situation.
I recognize that this is putting you in a difficult position, having to find new care on short notice. If there is anything I can do to help with this process, please feel free to talk to me about it.
Thank you so much for your understanding. I wish you and your child the best of luck. You will be missed!
Sincerely,
Me
Hope it helps.
Excellent letter!! I look forward to more of your advice!! Welcome