So you think that your son’s being off the derech is all your fault? Join the club. We all feel that way. But eventually I came to the realization that everything is in Hashem’s hand, for some reason this is the way He created my child. I have to constantly work on my bitachon.
I spent a couple of years feeling guilty and hashing over everything and how I reacted and the mistakes I made. It only made me feel like a failure and enormous guilt. But then I stopped and started looking at all the good I did. I was very devoted to this particular child and did so much and money and time was of no object when it came to this kids health and well being. My husband is an extremely kind and devoted father, my kids adore him.
What I’m saying is that not everything is in our control, Hashem is the only one who is, and we have to daven for His rachamim that everything will turn out for the good.
I hope this helps you.
By the way, I love Aries comments. excellent. Good Shabbos and hang in there.