Ok, so, it seems that there are two views on this subject as shared by some of you.
1. His relationship with his children is his responsibility and I don't need to expend my energy in trying to "fix" it.
2. While his relationship is his responsibility I can help by accommodating more palatable interactions and keeping him informed
of familial occurrences.
There's a lot more to those but essentially it boils down to these definitions.
After spending time thinking about this and pondering, I'm falling into category 1. The suggestions by BobTheBuilder:
1. Give him some conversation prompts for the next family gathering.
2. Send him a text message every couple days with a short "family download." He feels disconnected so hook him up!
3. You said he's into "computer games" but that covers a pretty wide area. Does he enjoy anything multiplayer? Or are there other interests of his that you could base a family event around? People are always more interesting when they're confidently in their element.
are things I already do (except the giving him prompts, he doesn't have an issue with having conversations with them, just doesn't ever have an in depth conversations because they make him uncomfortable-even when it's me and the kids having those conversations, he'll leave or try to change the subject, he gets physically uncomfortable).
We play D&D every week and he whole heartedly participates because he loves it. He can have an hours long conversation about the races and classes, what gear or magic items are better, which multiclass has the best stats, etc. etc. These interactions are easy for him and we all have fun doing it. But try and get him to go to something he's not interested in, forget it. If he was physically here he would go to graduations (military so for two of our kids he was TDY). But I can't tell you the last time he went to any other kind of function, even if he was available. Like I said before, he would usually make up an excuse and the kids and I stopped asking him. He actually coached soccer one year for our oldest son and went to most games (he would even leave work early for some), but once our son stopped being interested in it and quit, that was the end of WH's interest as well.
Basically, if it was going to inconvenience him, he'd rather not.
I also keep him in the loop with anything major going on with the kids, I have been doing this since the first one was born! I do remember him going to a handful of doctor's appointments when the first two were very young, but after the "Panama" incident, there was distance. I know I was responsible for some of that, but that only deals with our marital relationship, not the kids.
Pondering the last conversation we had, when I offered the idea that it wasn't too late and that he could change the dynamics of his relationship with them, he backpaddled, saying that well, he didn't ALWAYS feel that way, and that he was OK with knowing that they knew he would always be there for them if they ever really needed him, and was in fact CONTENT with the status Quo. It more and more seems like he just wanted to be seen as the victim, even though the dynamic is of his own making. Much like his disappointment of our lackluster bedroom. It took 2-3 years after the end of the A and almost a year of real IC for him to realize that my lack of interest had more to do with his treatment of me than whether or not I was still in love with him and sexually attracted to him. But while he's interested in rebuilding our relationship, he doesn't seem to have the desire to do the work for his kids.
Am I making sense? I feel like maybe I'm complicating things.
Anyway, at this point I know I am the conduit he uses to KNOW his kids. If we were to separate (or something happen to me), the kids would try to stay connected, but knowing WH, he wouldn't respond in kind and they would probably gradually drop off and he would be alone. He has said so himself in MC. So he knows, but won't lift a finger to change things. And what use is there in beating one's head against a stubborn wall?