I'd be really worried. I won't leave a step away from her. (I'll just use "her" because it's more common with ladies.) I'll distract her away from her suicidal thoughts. Go out and have fun with her. I'll try as much as I can to lift her spirit up. I'll help her deal with the problem she's facing at the moment which is causing her to take her own life. Life is full of problems. I'll tell her that she's not the only one with problems. As long as there's life, there's hope. If you fall down, you must stand up again. If you fall again, stand up again.
At least, I'll let her know that she has a good friend like me to care about her. I'll let her know that I'm worried because I care about her. I'll encourage her and give her all the support I can. I'll also get her to consult a psychiatrist. If she has some psychological problems, it's the doctor who will find out and treat her. I'll tell the other friends and her family to encourage her and take care of her.