Am I wrong for being upset that my husband told his sister something I specifically asked him to keep private?

I’m struggling with how to handle something with my husband and his family, and I’d really appreciate some outside perspective.

My brother and his family are in the process of buying a home and relocating to the Ocala, FL area. This is not finalized yet, so I specifically asked my husband not to tell anyone about it until everything was official, because I wanted my brother and his family to decide when they were ready to share the news.

My husband’s sister lives in DeLand, FL and is a realtor. She has also been pushing us pretty hard to spend Thanksgiving at her house this year. We’ve already decided we aren’t going, and apparently while my husband was explaining that Thanksgiving might be complicated because of family plans, he mentioned my brother potentially relocating to Ocala.
I don’t think he intentionally betrayed me. I think he was being pressured about Thanksgiving and the information just slipped out. He apologized when I told him I was upset.

The problem is that his sister immediately told me during a phone conversation we were having, saying something along the lines of, “Why didn’t you refer them to me? I’m a realtor.” So now I know she has the information, and I’m almost certain she will tell her mother too.

What really bothers me is the larger dynamic.
There have been situations where his sister has specifically asked my husband to keep something private from me until she was ready to tell me, and he respected that request. So I told him that when she asks him to keep something confidential, he is able to treat that as a firm boundary, and I need my requests for privacy to be treated with the same respect.
I’m not asking him to choose me over his sister or to stop talking to his family. I just feel like when I, his wife, explicitly say, “Please don’t share this yet,” that should carry the same weight as when his sister asks him to keep something private.

He apologized and I don’t want to turn this into a huge marital fight. But I have this lingering bitter feeling because now information about my family’s plans is circulating in his family when I specifically asked for it not to.

And now I’m wondering how to handle the extended-family part.

If his sister or mother brings it up again, I don’t want to confirm details, give them a timeline, or get pulled into discussing my brother’s move. At the same time, I don’t want to make it obvious that I’m angry or create a bigger family issue.

How would you handle this going forward?
Would you simply say something like, “Yes, they’re considering a move, but nothing is finalized and I don’t want to discuss it until they’re ready to share,” and leave it at that?

And would you address it with the husband’s family at all, or just let the husband handle any questions since he was the one who disclosed it?

I’m mostly looking for advice on how to establish better boundaries around family information without creating unnecessary drama.