Quite a ponderous question. I've been thinking about it for a while, because I dislike my father, mother and sister (no one left in the family, except the cat... I LOVE the cat!)
OK, what I think is that if yo love someone you still have to find out the correct way to demonstrate love. Comforting and nurture at atimes, but also pointing out problems.

So, you dislike your brother. If he was a stranger you would turn your back on him. You show your love by being available to help. But help also means NOT overlooking your borther's alcoholism and letting him be loved without being pushed to amend himself.

In other words, loving doesn't mean unconditionally cherishing. For me you proove your affection with this post. Your attempt to relate properly to your brother. If you would not love him, you'd just blacklist him and go on your way.

I'm not going to cite an italian proverb, as it may seem I trivialize the matter, but I think I've made my point clear.

The best of luck!