Export private key file from the pfx

1.  Its very simple, Just try with this method

openssl> pkcs12 -in filename.pfx -nocerts -out key.pem

2. Export the certificate file from the pfx file

openssl> pkcs12 -in filename.pfx -clcerts -nokeys -out cert.pem

3. Remove the passphrase from the private key

openssl rsa -in key.pem -out server.key