how do I support her and not lose myself in the process?
By taking the BEST possible care of your SELF and your minor children as you possibly can. You can help NO ONE if your life becomes unmanageable. You cannot "help" her through this. She has to learn and practice doing it her SELF.
P.S. Being there at her every call is not helping her. A person, especially when they begin Recovery, needs to learn that they can do it themselves. That they do not NEED anyone to be successful at this. They need to be courageous themselves, and feel the sense of accomplishment from doing so. Be supportive by sending a card and calling once a week. Not by being a life preserver. At least this is what I had to learn to do with my brother.