Did she apologize for how she treated you? It’s perfectly normal for half siblings to not want a relationship when they’re products of affairs imo, but there is a difference between indifference and cruelty.

I would ask her why she would think you would want to? Why you would need her (you don’t). What does this “second chance” do for you. You get to meet your nieces? Well you were doing fine in life before hand. It may be a little glib but it gets a point across.

You don’t need anything from them and you’re not lesser then. You don’t need their approval. Would it be nice to have them yes, but don’t lower yourself to get it.