I am so very sorry for your tragic loss.
I have a friend who had a son younger than your son.
She let him spend the night at a friend's house one night.
A man escaped from a prison and found his way to the house where my friend's son was staying. He axed everyone in the house to death including my friend's son.
I am sure she thought if she had only said he couldn't spend the night with his friend that night that her son would be alive and safe today. If you take addiction out of the picture the circumstances are similar.
Your son had a place to live with his boss who was willing to look after him. He was just visiting his new girlfriend and this tragic event happened. It is no different than a normal person without addiction visiting a girlfriend and having the same tragic event occur. It is not different than my friend letting her son spend the night at his friend's house.
When we make our tough love decisions that are in our child's best interest we are willing to go through the terrible pain our decisions cause to give them the best chance they have to find recovery. Rescuing our children just allows them to repeat the same vicious circle of addiction they are trapped in. I rescued for 20 years and have the experience to prove that it did not help.
I just left my son stranded in another state knowing no one. He found is way to a state 3000 miles away from me. I left him out there. I can't describe the pain of doing that. I know the risk of him dying. He is now in a treatment program. It was his only choice.
Your son's death was completely separate from his addiction. Your choices and actions did not cause this. We take the same risk when we allow our teenagers to drive. Your son was in the wrong place at the wrong time.
I am so sorry for your pain. It is not your fault.
Hugs and prayers.
MG