My Cydia was crashing every time it opened. I traced it to corrupt files in /var/lib/dpkg/updates. Deleting them fixed Cydia. I can't guarantee that will fix Cydia crashes but it has worked for several people who have asked the same question here recently.
Here are a few methods to delete them.
SSH into the phone and type "rm /var/lib/dpkg/updates/*" (without quotes) and hit enter.
Open MobileTerminal on the phone and type "rm /var/lib/dpkg/updates/*" (without quotes) and hit enter.
Use the apps iFile or Discover from Cydia to browse to /var/lib/dpkg/updates/ and swipe the files then select delete, or in iFile select edit, check all the files, then tap the trash can at the bottom.