Still not done...

I don't know how to do this. I hated quitting all my other jobs, even if I didn't like them and those were regular jobs. This is like quitting a family. Not my family and I don't feel like they are family, but they feel like I am. The grandmother is here visiting (her mother, not his whom I don't care for) and she told me today that I have a way with S that no one else has, not even her parents. She said that she tried for 15 minutes to get S to eat her banana when they were outside together and I was inside with the baby, and she refused. All I did was come outside, told her to eat it and she said okay and it was gone in a few minutes. After hearing that, how am I supposed to talk to them and tell them I am quitting their family, I am leaving their kids that I love as if they were my own, and walk away? Don't get me wrong, I want to leave this job more and more everyday. I don't enjoy it anymore. I am bored, I don't feel challenged. I feel like I put my life on hold and gave up my identity. I left my friends and family behind. I am glad I did this job, it was an adventure and I can cross it off my list, but it is time for me to go. But that doesn't make it any easier. Twice tonight I looked the mother in the face and the words were on the tip of my tongue, but then she would say something with a smile (she always smiles when she talks, I know where the baby gets it from) and I lost my nerve. So I have decided I need to write them a letter. I know the downside to that, but I can't do it any other way, not while they are looking at me. It may be a letter just saying I want to talk to them about my future with them, or it may go into full detail. Either way, I will let them know I want to talk about it in person later, but this was the only way it could be done. So thanks for all the advice and support. But I have to do this my way, and this is the way it needs to be done. Otherwise I will be here forever.