"the last thing I told him was, take the trash out when we get home, not I love you or good luck"

That was deep, and ofcos it's had to know such a thing would happen. Back to question, what i would do for you if i knew.

I would let you open up to me, because mostly in our lives we don't listen to our beloved ones. That would make me feel better about you, and you about me as well.
It's beautiful to listen, and not just listening but to understand our beloved ones.
Eitherway it wouldn't take away the regret but still i would feel like i gave you something so valuable.