Imo....
You seem to think you can handle the relationship if it becomes an open one. I get the feeling that you have never done this before, but you are open to the idea. Therefore I propose that you go in, eyes wide open, tuned into how you are feeling, and try it.
Everything in life had the potential to be a learning experience. Since you are so cognitively aware of the entire situation (i.e. in healthy contemplation of what could go right, and what could go wrong) if you don't mind risking the relationship that you have with her, i say give it a try for the experience.
You may love it, it may be a great fit for you, or you may hate it. But you won't know, the curiosity won't be satisfied, too you give it a shot.
The one issue is that you have to be sure she isn't doing this to try and get back in as a significant other. Are her motives pure? If not, that could complicates things
Good luck