detaching is not apathy. detaching is seeing them as a whole person that is separate from us. It is understanding that their journey is not ours.
I don't think that encouraging them is co dependent....but if you have to know every little thing and be their constant cheerleader? yes.

our recovery is learning that their world is their universe and journey and that we have a special one of our very own....that it is usually dusty and unloved and needs to be taken out of storage and shined up and enjoyed.

I try to treat everyone well...I would never treat my addict less well...and I tried not to treat him better...sometimes I used the idea that "if this was a stranger, what would my choice be"

and sometimes, I just don't know. that is ok too...as they say, progress not perfection.

Thanks, Blueviolet that makes sense :)

I want to add a bit from our friend Cardinal, who lost her daughter to a drug overdose last year. About boundaries:

she said "say it in 15 words or less and don't bother to say it if you aren't going to follow through".

A wise woman, who continues the fight for others, and still loves her daughter, now free of her addiction at last.

Think about it like this, substitute diabetes for alcohol problem. We don't stop loving them do we?

Are you more focused on the other person than yourself?
How do you react if they are not taking care of themselves?
Do you involve yourself in enabling their problem?
Do you find yourself criticizing that person, changing you life to accommodate them to your detriment or are upset all the time?
Has their problem snuffed out attention you use to give to yourself?
What are your conversations centered on with this person or with others? Do you always talk about helping them, wishing this or that for them? Are you taking care of that person.?

The above examples were ways I thought I was being encouraging yet I was behaving codependent. I like the 20/80 rule. You get the 80 %.

Great replies here. Another point worth mentioning is that the person on the receiving end of our boundaries may not be willing or capable to agree that it's a constructive, healthy move. That's where outside support (via individual or group counseling, websites such as this one) is really helpful.
I was married to a man with Borderline Personality Disorder -- which is called the disorder which exists to deny itself. My setting any sort of boundary, however calmly and rationally, would at least initially provoke his anger -- I guess because of a perceived loss of control over me.
It's on me to discern whether any of that has impacted my relationship with my siblings. I certainly lost tolerance for half-truths and outright lies to save face at my expense. Any boundary set by me has been met with more emotional abuse in return -- in fact outright resentment for my talking the high road.
I've needed to go no-contact for now, and that enrages my brother in particular, that I won't be bullied or baited. Underneath that, he loses me as a target for projecting a boatload of bad feeling inside himself.

I meant taking the high road -- Spellcheck didn't agree.
One more comment -- that no-contact is a last resort after a lot of attempts to reconcile or find common ground. It was affecting my health, so I appreciate the 80-20 reminder.

Boundaries are for you not the addict, yet at the same time you need to be encouraging them to help, but don't nag. Healthy boundaries are for example; no using drugs or drinking when that person is around you. If they are high ask them to leave and tell them you love them and would be happy to be around them when they are sober. If married go into another room, but continue what you were doing. Don't make rules for the addict, they will not follow them and will resent them, instead the rules are for you. I did not like alanon, and preferred Smart Recovery. Here is a good page for setting boundaries.http://www.smartrecovery.org/resources/family.htm