One of the common things all well-hearted ppl do, is blame themselves for whatever bad happens. It was not your fault the whole incident happened, and i know it has already been five years since she passed, but love never dies and neither does the memories. But as you graciously wrote, time is a great healer and it does heal, but the scar remains. God bless the departed soul, she at least got the chance to be loved. And i bet, she lived more life in her short time in earth, with a loving man like you, than most of the ppl will ever get to live in their lifetime.

Dont be hard on yourself, learn to let go.