but I worry about my anger flaring up
One of the most important and life changing things I've learned in this journey, is that nothing is personal. It's a choice to make or take anything personally. I intellectually grasped that before I accepted it, and it was really hard when I was face to face with my daughter when she was acting out.
When she was out of control, my habit of wanting to control kicked in, and then I'd get really angry because I couldn't control her or her actions, anger, pain, etc. I was so focused on her issues I didn't realize it had become an issue for me. My responses to all of it did not resemble love in any way, shape, or form. It didn't feel like it, either.
So my therapist asked me, what does love look like to you? And that's how I began to change my responses. I treat her with the love and respect I want; it does not matter how she treats me. I am lovingly firm with my personal boundaries and we both benefit from it. I had to fake it 'til I made it, though, because it was so foreign to me.
If you're able, please consider seeing a therapist who specializes in addictions and families. Your son's rehab can probably give you a few referrals. The one on one time to work on changing my responses has been invaluable.
Congrats to you on your recovery!