Matt what kind of help are *you* getting for YOU?
You can't control what happens when she gets out of rehab, how she'll feel, what she'll want, or who she will be. If she is going to beat her addiction and fully embrace recovery, it's going to take a lot longer than 28 days, and she likely won't have the bandwidth to handle the demands of a relationship.
*You* are not her issue. Her issue is addiction, and it's going to take everything she has to recover. Your desire to hold and comfort her is all well and good but not what she needs right now. She needs the professionals at her rehab, and the time and space to get herself together for the fight of her life. That's not a battle anyone can fight for her.
In the meantime, there is a lot of help for YOU out there to let go of your fear of what might or might not happen and life your best life regardless of what happens to her. Have you been Al-Anon or face-to-face individual counseling?