Mike
I think you did the right thing, for yourself and for her, by just being honest about your feelings and where you stand right now. Because you were honest and straightforward, doesn't mean that she will receive the news well, but that is her issue and not something you need to feel guilty about. And what she said about new medication and feeling suicidal was probably a guilt trip being laid on you, and you don't have to take ownership of that either.
She will be how she will be, today and when she gets out. If she wants recovery, she will find it and work her own program, whether she is with you or not. If she says she needs you to stay clean, you know that is a red flag, because nobody can do recovery for another person.
In the meantime, my suggestion is to keep working your program, and stay focused on you. If she will be getting out soon, maybe sit down one day soon and write out what YOU want out of life, and if it includes her, perhaps some boundaries that are about what you are willing to live with and what you are not, and how you will handle yourself if things go bad.
My fellowship is CoDA (Codependents Anonymous) and close to half of the members of my home group were also recovering addicts or alcoholics, who were dealing with issues of codependency just as you are. Working the two programs together (CoDA and NA or AA) seemed to be a good solution for them as one enhanced the other. Also, there is nothing to stop you from going to Nar-Anon or Al-Anon if CoDA is not available. Contrary to the belief of many addicts, these fellowships are about US and our issues and codependency, and not at all about what substance the person we loved used. You might want to try one of those meetings to see how you feel.
Also, you are more than welcome to visit to Al-Anon or Nar-Anon boards here and share your concerns and maybe get more feedback from others who have been where you are.
The important thing is to take care of yourself first. You are the only person to whom you are accountable.
Hugs
Ann