Hi Meghan,
Great advice as usual from pilot and I would say the same. Respond with PMA. Keep it brief and talk about a few things that are going well with you, or new things you tried lately. If you are funny, maybe say something that will make him smile.

Pilot's advice to ask how he is doing is interesting. I always take the opposite approach. Maybe I've been doing that wrong!? Interesting! How I usually do it is stay upbeat and ask something like "how is it going in (new city)? Are you loving the (weather, traffic, whatever)?" Keeping it light and maybe making a small joke of it. Acting like nothing bothers me and I'm totally cool with the fact that he moved out.

Looks like you've gotten some good feedback thus far. Let us know what you decide to write!

Hugs, Lisa