While I am unaware of the nature of your son’s death and the events surrounding it, it is apparent that your daughter was also affected by it.
As you are well aware, your wife’s drug addiction has not only impacted you and your marriage, it has had a profound effect on your children. Children naturally look to their parents as a source of stability and comfort. The drugs robbed your daughter of these qualities in her mother.
Before being able to heal, your daughter needs you to understand that fact. As an adult you are able to trust and forgive your wife more freely based on your previous experience and relationship. However, your daughter has been deeply hurt and will need time to renew her relationship with her mother.
She needs to learn to be able to trust her again. She needs to re-develop a relationship with her “real mother’ and this will take time. Recovery for your wife is a life long journey. When she comes back home, there will be ample and adequate time for mother and daughter to re-develop and renew their relationship. As she goes through the twelve steps of recovery, she will learn about making amends to those whom she hurt.
Based on my experience, true remorse and regret is usually met with acceptance and love even if it takes some time.
While I do believe your daughter would benefit greatly from participating in the family weekend, conversely, if she is forced to attend she won’t be open to learn all they have to offer and might grow to reject and resent the process.
Your daughter needs your unconditional love and support right now.
Invest in her needs and may you be zoche to reap the fruits of your labor.