I wish I read this message sooner. Thank you for the advice.
I ended up responding politely to my ex's dad, saying that I was dealing with things as best I could even though it's been difficult, but I also thanked him for supporting our relationship. (We were relatively close because he also used to videochat/talk to me a lot during my visits.)
He responded hours later with, "I don't know what happened. But (ex's name) hasn't been himself these last few days. He's broken, hurting. I caught him doing this tonight." And then he attached a picture (taken from behind) of my ex hunched over a bar table, taking pebbles from a decorative pot and putting them together in front of him to make a heart figure. His hair was longer than usual and he lost weight.
I couldn't reply anymore. Seeing that picture of him wasn't anticipated. I know his dad meant no harm. He truly supported us as a couple before. But my emotions came flooding back in and I suddenly felt a this wave of intense pain in my heart. I burst into tears and cried for two hours afterwards.
In the first hour of crying, it took every fiber of strength in me not to reach out to him and comfort him.