This isn't all about her illness - she has affected her family for a long time.
A long time ago now, I had to confront my father with something really horrible. I spoke with numerous therapists prior to confronting him. In all cases, they ended by saying "If he commits suicide, you must remember that it is not your fault."
Remember what you yourself just said: This isn't all about her. You have to take care of yourself. If she does commit suicide, it is not your fault. If you spend your entire life miserable and always trying to control a situation (your mother) over which you have control - that IS your fault.