I've had an ex boyfriend die (not the same, but it's what I've got).
It's certainly a weird feeling, that you survived, and he did not.
Sorrow, I'm sure, is utterly appropriate. But so are some regrets. It's not that you loved this guy more than you love your husband; it's more that we naturally as human beings tend to think of 'what if?'. And when there's a death, that 'what if' impulse strengthens.
Consider counseling if, say, a month goes by and you still feel wonky.