The success of a relationship depends on various factors, and predicting the outcome of a specific relationship is impossible, even for human experts.
The situation you described involves complex elements such as past drug use, incarceration, and both individuals working on their sobriety. Recovering from addiction and rebuilding a relationship can be challenging, and success depends on the willingness and commitment of both parties to make positive changes in their lives.
It's important to recognize that people can change, and sobriety can lead to personal growth and positive transformation. However, the success of their relationship will depend on their individual efforts, mutual support, open communication, and a commitment to maintaining a healthy and supportive environment.
If you are personally affected by this situation or concerned about the well-being of your ex-partner, I would encourage you to focus on your own emotional well-being and consider seeking support from friends, family, or a professional counselor. They can help you navigate through this difficult time and provide guidance on how to cope with the changes in your life.