Instruction how to split a .pfx certificate into separate key and certificate:
Extract key
openssl pkcs12 -in [yourfile.pfx] -nocerts -out [keyfile-encrypted.key]
Decrypt key
openssl rsa -in [keyfile-encrypted.key] -out [keyfile-decrypted.key]
Extract certificate
openssl pkcs12 -in [yourfile.pfx] -clcerts -nokeys -out [certificate.crt]