There were a lot of problems with Cydia recently and I kept posting my solution and it worked for some people, so I've just been pasting the same thing. It may not work for you, but it won't cause any problems as Cydia will reload the files you delete if it starts working, so here goes:
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.
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There is also a thread
here with possible solutions, but I can't vouch for them.