I do not think the message was about Max at all. I think it was written by RN in 3rd person, as a way to disconnect from her life, as she was about to end it all anyway. The only other female hanging suicide that I know of personally included a note, left by the teen girl. It was also written in the 3rd person, and began " Once there was a girl.."
I think she was reminding JS that she had 'saved' him. Saved him from his violent and angry prior marriage, from his lonely previous life. I am sure her young, beautiful vitality was like a life saver for him. He probably told her many times that she 'saved' him. He was in a very difficult marriage in which they called the cops on each other several times, IIRC.
So, imo, she was angry at JS for allowing DS to ban her from the hospital, to accuse her of being at fault and she was especially angry that he did not stand up for her against his ex. Then when she got that late night call, where she may have been told that Max was essentially dead, with no chance of survival, she was devastated further. I think that JS may have unloaded on her emotionally. " You were supposed to be watching him. How could you let that happen--PLEASE move out now, I cannot even stand for you to be there when I come back."
I really believe he would have said some things along those lines. So she angrily reminded him that she SAVED HIM--and then taunted him by asking IF he could save her. Obviously she knew he could not.