Kill him, or accident? [HELP]

Sorry, no. I'm not contemplating murder. Well, a real murder. I am an amateur writer. I have this plot point for a story I'm writing, and I'm not sure what route to take. I want to hear some opinions. I'm going to summarize as simply as I can.

There are two 16-year-old twin sisters. A and E.

E runs away to the city and gets mixed up in a bad crowed. E starts dating a punk in the city who introduces her to drugs. E becomes obsessed with the boy, possibly brainwashed (I have reasons).

A thinks E is not herself anymore.

A becomes jealous of all the attention E is giving to the boy. A hates the boy, and blames him for turning E into a drug addict.

E dies in a car accident, and A blames the boy for her sister's death.

A confronts the boy.

A finds that the boy is a mess, mourning E's death.

So here's my conundrum. 

The boy is to die. He's a character destined to die. And when he dies, A is haunted by him. It starts as maleficent haunt, HOWEVER, over time he becomes a sort of a protector of A. Kind of like a knight. The idea is that he is redeemed in death. 

Now. I'm not sure exactly how I want him to die.

1. A kills him in self-defense. 
2. It's an accidental death--coked up, he tries to attack A, she pushes him, and his head goes splat on a corner of something.
3. He is murdered by some other plot point that I haven't thought of.

I'm thinking either 1 or 2. I like 1 because it's not a passive decision. It's character defining for A to kill someone..right? What I like about 2 is that it mirrors E's accidental death; HOWEVER, it is more passive. With 2 a would still feel guilty and blame herself for his death, but she could always fall back on it as being an unfortunate event. Huh...I could also see 2 as being especially grey, as A could struggle with the idea of maybe it wasn't an accident, and she always wanted him dead. I guess that would make 1 the more passive choice...right? Because the boy basically made the decision for A, attacking her, and making A kill him. 

UGGGH



Option 3 only exists because a scene/image came to me of the boy stumbling towards A. A thinks he's on something, but discovers that he was stabbed. 

I realize there could be an option 4 where she kills him in cold blood, but it's not A's character to do such a thing.

Even though I feel as I'm even further from making a decision, I think this helped. Maybe I should write all three scenes and see, which fits better.