Think of it this way:
Your ex was first on the scene of a fatal crash and he used that tragic event in an attempt to weasel himself back into your life. How do I know this? Richard tried the same tactic on me (the scenario was a bit different, but not much).
When Richard was actively drinking he didn't feel or show compassion for anyone. But he never passed up an opportunity to try and weasel himself back into my life. Most people would see a stranger's death as a tragic event; Richard saw it as an opportunity.
When I looked carefully at Richard's motives, it was easy to enforce my no-contact rule.