I can see your concern, and admire your caution. But, go for it! You aren't going into it 'blind' or with a barely concealed desire to cure all the addicts.
I did psych for 17 years, four of them in chemical dependency. It was by far my favorite job (I know, imagine that) of the psych persuasion. We were a free standing hospital with 16 beds, like a middle class Betty Ford. Watching people come in covered with abscesses and leave with 20 well needed pounds and a light in their eye was worth every heroin addict cursing me and my grandchildren.
I too had family members with drug and alcohol problems -- my husband at the time. So I'd go to work -- addicts and their shenanigans. Go home -- addict and his shenanigans. I didn't know what end was up. If your addict family are not in your HOME, your experience with them will only enhance your motivation to excel. Addicts are a very draining bunch, but just imagine what THEY are going through. If you are fine with believing none of what you hear and half of what you see WITH objective evidence, you will thrive in addictions nursing. If you don't have a secret narcissistic streak and think YOU will heal them all, and you have good self-management skills, good stress relief and self care (you'll need it), I think you will be glad you took the risk. I prefer nursing with a little bit of a 'kick' myself, and you never knew what was gonna happen in addictions nursing. That made it more fun for me. If you are pretty OCD and don't like surprises or changes in your routine, I'd advise against you going into addictions
Flexible and non-judgmental personalities do the best in this field, IMO. And your interpersonal boundaries will be an ever evolving thing.