I believe you are right about your son and GALing.
There is so much advice out there about what to do. While he is seeing someone else, there isn't much you can do.
for us, I've been dark for a long time. Only because it opens up wounds that are so raw. My wife seems to be doing very well with things.
Unfortunately, it is the kids who have to deal with it. We do nothing as a family anymore. Holidays, special events, are done seperately and alternating.
Do what's best for you and your child. I'm sorry we find ourselves here.