I found the old versions have been kept on my disk:
sudo find / -iname 'textmate*' … ~/Library/Caches/com.macromates.TextMate/TextMate_2.0.tbz ~/Library/Caches/com.macromates.TextMate/TextMate_2.0-rc.31.tbz ~/Library/Caches/com.macromates.TextMate/TextMate_2.0.1.tbz ~/Library/Caches/com.macromates.TextMate/TextMate_2.0.3.tbz ~/Library/Caches/com.macromates.TextMate/TextMate_2.0.6.tbz ~/Library/Caches/com.macromates.TextMate/TextMate_2.0.8.tbz ~/Library/Caches/com.macromates.TextMate/TextMate_2.0.10.tbz ~/Library/Caches/com.macromates.TextMate/TextMate_2.0.11.tbz ~/Library/Caches/com.macromates.TextMate/TextMate_2.0.12.tbz ~/Library/Caches/com.macromates.TextMate/TextMate_2.0.14.tbz ~/Library/Caches/com.macromates.TextMate/TextMate_2.0.15.tbz ~/Library/Caches/com.macromates.TextMate/TextMate_2.0.16.tbz
Q