Relationship help, what would you suggest?

Here is the situation…There is a person that has a crush on me, and there are mutual feelings of attraction. We have countless mutual friends, and see each other often in social gatherings among friends.

The problem. This person that has a crush on me dated a sibling of mine for over 4 years. They have been broken up for over 2 years now, and this person assures me they will never get back together.

I know my sibling very well, and am pretty sure would not take this news lightly. This seems to be the only obstacle in the way of what would seem to be a good relationship between two very good friends.

A secret relationship seems pointless, as we could never be seen in public with our friends as a couple, and would only make it worse once the sibling found out.

I guess the question is something like, if the sibling doesn’t like the idea of it, and won’t be okay with it. What would be your next step? What would you do in my situation?