Stickywater,
Relapse is always a possibility, especially early on. She is trying to learn a whole new way to cope with life on life's terms. She may not "get it" the first time, the second time the 20th time.
Until YOU learn as much as you can about addiction, I think you will always be in a vulnerable and precarious situation.
Based on that, I don't think there is any way that you can make any decisions about anything.....other than to decide to put some solid boundries to protect your son, yourself....and most of all (to whatever extent possible) your heart...until such time as she has proven that she has these tools well learned and in place.
Rehab is not a cure. I learned that one the hard way with my daughter. Addiction is forever. But recovery can be forever too....she just has to want it...and want it bad.
In my way of thinking....doing Whippets in SL still shows the drug behavior.
They are taught People, Places and Things. To be sober and in recovery means giving up the people, places and things that they had while using. As well as anything that could be a trigger to use, or to start a new addiction....like casinos, bars...etc.
Some addicts will replace one addiction with another. Her drug of choice was heroin, but she could replace that with excessive shopping, or gambling or something else. She needs to learn how to use the coping tools she was given in rehab to identify and stay away from anything that is not condusive to sobriety and recovery.
From my experience....addicts in recovery, who are embracing their recovery....and working their program....are humble, feel guilt and shame and take proactive steps with humility to attempt to un-do the damage their addiction caused. They do this by cleaning up their own problems, accepting and living within healthy boundries set by the loved ones.
And when they are doing this....it is my experience that you will KNOW. Their efforts will shine like a beacon in the night. There will be no question. Then comes the sustainability portion....they need to do this for quite some time....
The most loving and solid thing you can do is to set healthy boundries for YOURSELF and for your son. In doing so, you are loving her. Even if you decide to end things with her, you are loving yourself first....protecting and loving your son....and loving her.
I would suggest one year from the time she gets out of SL. If she can sustain her sobriety and recovery for one year and get that down solid...then you could start thinking about, working on....your relationship from that NEW and HEALTHY starting point.