I think a good thing to realize here is that just because you have an idea of what they’re going to say, you don’t and can’t really understand how they feel about it and letting them say it allows them to express it to you.
Instead, wait on them to finish and restate what they said in your own words, asking if you have it right. They may have some clarifications, in which case your irritation with knowing what they’re going to say is going to seem silly.