I'm sorry for the loss of your friend. <br />
In reality, he didn't kill her. He is an idiot for making the suggestion to her to take "a bunch of pills" but in the grand scheme of things, she was an adult and has to be responsible for her own actions. <br />
Just do your thing, go to the downstairs and hang out and have meals and just steer clear of him.
You are obsessing about him too much.