Sorry about your son, I was a lefty when I was young (33 now) because I fell for the propaganda. It's something you have to experience yourself I think, or else there is always an excuse you can make for leftism to keep you in the cult. Only when you live it for long enough can the spell be broken for some people.

Good luck, just know there is hope. The best thing you can do is be an example of a great person, so it's hard to rationalize you as the "bad guy".