Boot camp unexpectedly quits every time i try to open it

Create one now, so you have the latest backup. We can then try to clean up. The worst-case option is to erase the whole internal disk after the backup and then restore the backup.

See

Back up your Mac with Time Machine - Apple Support

Restore your Mac from a backup - Apple Support

for reference.

Do you have a Time Machine backup of macOS? If not, can you create one now.

Did you remove Windows using BC Assistant?