Ok, if this person has told you how and when call 911 get them to their place if you know the address.

If this is a future thing, call a crisis hotline they can help you to deal with this individual as well as the effect it is having on you.

I am sorry you are dealing with this, I have not had this particular issue but I have dealt with emergencies with friends that caused serious drain. The best I can say is: you are not responsible for this individual's actions. Wanting to help is a great thing it speaks twoards the kindness of your personality. Ultimately though whether or not this individual accepts your help is their choice and not on you.

Hope this helps.