I am sorry that you are going through this. I too spent years thinking of the things I did that could have caused my kid to go Off the Derech and I spent years blaming the people who misunderstood my child.
I know now that it was time WASTED. It does nothing to help your kid. And he will pick up that you hate and blame “Haraidim” (I hate that term) as well.
Forgive me for being honest. Hang on, this is not over. Keep up your Tefillos. At least he is not home doing nothing, let’s hope he continues school. all the best!