some news about the possibility of Bitcoin double-spend...
which turns out did not happen.

Bitmex 'reported' this story... they just wanted to liquidate longs.
First possibility:The double spend did not happen indeed. Read the actual news,
https://www.coindesk.com/bitcoin-double-spend-that-never-happenedSo, that was a FUD by the media. I don't know if such kind of news has a power to bring down the market to this level. I don't think so!
Second possibility:A record $3.7 billion worth of Bitcoin options are set to expire on January 29, 2021. Quote from the source:
https://www.businessinsider.co.za/bitcoin-price-options-record-expiry-speculation-derivatives-2021-1The options show that speculators are bullish about Bitcoin. As of Monday the open interest in "calls" (which are broadly bets that prices will rise) was considerably bigger than the open interest in "puts" (bets the price will fall).
So if I have to believe the above, the price shouldn't have tanked.
I strongly believe that it is a market correction. Every meteoric rise like this has to correct in order to maintain stability in the market. A lot of people have sold their bitcoins and book profits, especially people from 2017 who finally had a chance to recover their lost money and pay off their debt. So it's a healthy corretion. The market will be back on track quite shortly.