I know than I am willing to post on this forum. And its not just family its good friends too. Trust me it was no fun hearing from a best friend that not only is he going OTD, he is going off the “straigned” path as well. That was a shock to me. And this was a Yeshiva guy no less.
I know more people than Id like to admit and none of them came back and I am currently dealing with someone who worked so hard to become religious and it appears due to attitudes and corruption in the community (Both Charedi and Modern , neither was innocent here) they are about to leave. I am doing my best to stop it, but there is only so much I can do. If I can keep them in the community I think they will stay for a while, but if they leave , they will be gone forever.
I can also tell you that its best to only practice tough love to a point, If you want to punish him in the house and make rules in the house that he must follow, that is ok, but NEVER throw him out, because that will likely BACKFIRE and backfire badly.
Unfortunatly many people here are telling you either he will come back or tough love will work. In my life they dont come back. Thats why I think you need to accept it.
Finally I think sending him to the US is a bad idea. Not because he needs the change, but because I fear it might get worse. At least in Israel he will go into the Army and hopefully meet a nice jewish girl. Maybe not religious as you would like, but I am sure a nice jewish girl and hopefully you will get some nice jewish grandchildren (Even if they are not religious) . If you send him to the US, Its very possible he will meet a nice shiksa. In Israel the Arab women dont usually go for the Jewish guys (The Arab men do want the jewish girls though) but here in the US many shiksas want a jewish husband (They think they make better husbands) And then not only will you have an OTD kid, you might have non-jewish grandchildren as well.