First, try this simple first step: Press and hold a Shift key, while launching Contacts from Applications or the Dock, whichever you normally do. Release the Shift key when Contacts opens (or crashes again). That action prevents Contacts from opening the card that was opened last time you used it. Determine if you can use Contacts without it crashing. If it crashes again, keep reading.
Next: Are you using iCloud for your Contacts? If you do read below. If you don't, please write back for suggestions.
Quit the Contacts app if it is running (which it probably isn't, because it is crashing).
Then, create a backup file of all your Contacts, because you want to be sure they are safely archived. To do that please launch iCloud.com on your Mac, and select Contacts.
Assuming all your Contacts are present, click the "gear" icon at the lower left:
Choose Select All. Then, Export vCard...
All your Contacts cards will then be downloaded to your Mac's Downloads folder. It will bear the name of one of your Contacts cards "... and <some number> others.vcf".
The Contacts app may automatically launch. If it does, it will probably just crash again. Don't worry about that for now because you didn't do anything with it yet.
Then: Restart your Mac in "Safe Mode". To do that please read Try safe mode if your Mac doesn't finish starting up - Apple Support. Determine if the Contacts app crashes while using your Mac in that mode, or not.
Then, restart your Mac normally and determine if Contacts crashes or not.
Let me know what you find out in both cases: while in Safe Mode, and after subsequently restarting normally.
