That is wonderful, HeySeuss. I am glad that he felt comfortable enough to open up to you. I tried to talk to a WWII veteran, my brother-in-law's father. He served with the 8th Infantry Division in France. He was with an Infantry battalion's Anti-Tank platoon. They used 57mm AT guns, towed by 6x6 trucks or jeeps. He would not say anything to me about it. In fact, he later told my sister to please ask me to not question him about his experiences. It saddened me greatly. He died about three years ago. :(
My grandfather managed to not tell me a thing about his time on the Pusan Perimeter. I had to discover the circumstances of his combat record through meticulous research after he died. I don't think anyone quite understand what he went through. My other grandfather was in WWII serving as a Seabee, which meant that they were attached to Marine units and so his service was also very bloody and he didn't talk about it.
I still really think that relatives don't want to open up to their own families, so yeah, Eddie opening up to me about the siege of Khe Sanh and Hue was unusual, and he disclosed guilty things about how he walled himself off from new replacements and didn't help them and it ground his gears for years afterward-- in particular, one guy was seriously WIA/KIA and he felt like he only told him, 'watch out for the RPG's' instead of screaming at him to get down or pulling him down. Still, he came out better for it once he started opening up to the point of talking to relatives and loved ones.
Now, of course, I am also certified in mental health first aid, but it turns out I was doing it right even when dealing with guys that were coming back early during Iraq and were pretty rattled. In most cases, it's simple. You let them do the talking and don't judge, but the fear of judgment thing is what seems to drive people away from wanting to talk to people, especially close relatives.