I've had that happen to me and it made me so mad! But in my case, it was my grandmother, and because I knew her well, I knew her intent was to insult me by saying that I was living an extravagant lifestyle by having two of something when really one should be enough.
I think choking on your drink was the perfect response! You don't owe her an explanation. She was the one out of line, not you.
Where we live, it's very snowy. I've had my eye on a very specific model sports car since I was 11 years old. When I was 21, I bought my first car, but I could only afford a practical car and I needed a reliable one, so I bought an economy car. When I was 29, I had paid off the economy car and it was still my reliable winter car. I then bought the (by this time old enough that it was a classic) sports car I'd wanted for forever. It's very impractical in the winter and so I could not sell my reliable economy car. And I wouldn't want to anyway because it's not worth much money and I also am unnaturally attached to it. I suddenly had two (albeit old) cars. And my grandmother thought I should give away my economy car. Not sell it, but give it away. I think my response was a non-Poker face very angry and horrified look and I said sarcastically "yeah right!"