I feel compelled to be snarky: you have a choice of regrets here. You can regret not being there for your brother, who is your best friend and who just suffered an unimaginable loss. Or you can regret not doing what your H would prefer. Seems like a no brainer to me.
I am striking out trying to rephrase that so it does not seem to be a negative shot at your H. It is not that I want your H to suffer. It is just that your H is asking for you to make a huge emotional sacrifice to save himself a minor inconvenience. Seems unreasonable to me. YMMV.