Welcome to mamapedia!
I'm sorry this is going on. it's not fun losing someone. Especially after TRYING to mend fences.
Your husband is GRIEVING. Tell him to breathe. It's tough losing a loved one. Being mad at them will NOT change his father's death nor will it change anything, except for him to have extra baggage.
Your marriage needs help - lots of help. You both need counseling. You cannot walk on egg shells and your husband needs to stop pushing you get other people upset because they didn't show (and 9PM is VERY LATE for a wake). You can tell the family members you missed them at the wake and be done with it. It's NOT GOING TO CHANGE ANYTHING.
You drove 8 hours to a nieces birthday party? Yeah. i'd be a tad pissed too. that's a hell of a trip for a birthday party.
Get into counseling. Figure out WHY you are the one working on it and your husband is not. You said in your post - "I have been trying desperately to make things work" - well is HE trying to make it work too or is he trying to make you his welcome mat? Marriage is a PARTNERSHIP. it's not a contest - it's a PARTNERSHIP.
WHY are you with him?
WHY do you TRY desperately to make things work?
WHAT DOES HE DO to make the marriage work?
Tell your husband that he is upset. You understand that - but in the overall scheme of things? Getting EVERYONE mad isn't going to change things or make it better. What does he expect from them? An apology? Maybe they should apologize - that would be the right thing to do. Find out what he wants to happen. Does he want a family feud? Is that what he really wants??
Remember he is grieving too. That makes people do and say stupid things.