Isn't it amazing how things change when you're in the 'here and now'? Great job!
I wouldn't ask your son about anything that happens when he's with his dad, even if it's about cell phone usage. The kids time with their parent is their time with their parent. The person to talk to is your spouse. Goodness knows I keep accidentally putting the kids in the middle. It sucks not to be part of a whole, but then again, this whole thing is one big learning curve.