Even if a kid does NOT go through any kind of bad experience with another frum Jew, it does not guarantee that he or she will not go off the derech.
Of course as parents we have to try our best but this is a gzar mishamayim.
Unfortunately there are many such “tzaddikim” that are tremendous Talmidai Chachamim but they abuse their wives and children at home.
Now your son will know the hard fact of life. That just because someone is dressed in black and white and all yeshivish does NOT mean he is a ben Torah. He is going to find that out sooner or later and better he find that out while he is still under your roof and in your comforting arms.
Again, I am sorry that he went through an awful experience. Kol Hakavod to both of you for dealing it in an adult manner.
And keep on davening!