You've hit on a good turning point. Looks like you can make a breakthru' from here by improving the communication; at least be smart at doing YOUR part (that's what I like about you most).
Remember you can tell him calmly that you feel/want/think X,Y,Z but its up to him after that; you can't really control or enforce or expedite the outcome. (Easier in theory but takes a lot of practise and self-control esp. with all the established patterns and PTSD going on. I know his being on the PC is shutting off the rest of the family; he's so near yet so far away and he should know how you feel about that in a manner that has a good chance of being effective. I suggest you also be careful that your D is not mimicking what or how you communicate with him; he may have triggered his snapping at her for this reason. And snapping back like you did would probably just result in him getting defensive or feeling further attacked or "controlled". Looks like he really understands what "character" is so he may not have meant what he said).
