As a RA myself, I suggest some therapy or counseling so you can have good tools to deal with your feelings and emotions and set good boundaries. Alanon/narconon can help the family understand and cope with the addict.
Nobody can make a person be an enabler. That comes from not having solid healthy boundaries. But you can learn how to set boundaries and stick to them and a counselor can give you a ton of support through all of this.
I think 90 days in rehab is plenty. Six months maybe for some that are in heavy denial of being ill but the tools are given to the addict in the first 30 days. I personally would have gone screaming mad if I had stayed one more day past 90. But each person is different, unless you've actually been in rehab it is easy to think staying there longer would be helpful. I got what I needed fast and early and the rest seemed punitive and less about the recovery and more about rules.