I agree it was in no way wrong! Anyway what's done is done!
I do think that comparing really isn't helpful, though. And it's worth bearing in mind that some people really aren't capable of expressing themselves very well. It's hard with siblings sometimes to see what's really going on with them, and decide whether to forgive and forget, or make an ultimatum. I had to make an ultimatum with my sister today...

"...will you please either do what you've told me you'll do, or take the lead on the house sale, because it's getting close to the date of the auction...I can't be second guessing your actions, and making assurances to actioneers and solicitors."

So at the end of the day, with no straightforward answer to that question, it's all in her hands now, which is for the best. I got REALLY mad about it, but I don't expect her to change her ways.

I hope your sister does take what you've said to heart, and understands how important it is to be honest with you