There's a difference between detachment and the silent treatment.
Detachment says we dis-engage from the drama, the conflict, the mess, the unfulfilled promises, the expectations that come with living with addiction. It is a means of keeping our serenity under very difficult circumstances.
The silent treatment is a punishment for bad behavior. You mis-behaved and now I am ignoring you. I understand that, and there were times when I was so emotional about stuff that it was the only tool in my possession. But there aren't any rules for it. You will let go of that when you are ready, and maybe you aren't, that's okay.
You can have a family dinner and still remain detached. Going out to dinner doesn't have to mean everything is okay. You are responsible for the silence and hostility, and only you can decide when that is enough.