Public key encryption and decryption with private key
You are trying to encrypt and decrypt with AES, which is a symmetric algorithm, using your RSA keys (which are meant to work with RSA, which is an asymmetric algorithm).

To use AES, both sides need to know the same secret key - there aren't separate public and private keys. The way you would usually do this is to choose a random secret key for AES (often called a data encryption key or DEK), encrypt the file using that key and the AES algorithm, then use RSA to encrypt that DEK using your friend's public key. You would give your friend both the encrypted document and the encrypted DEK. She would decrypt the DEK first using her RSA private key, then use the recovered DEK to decrypt the document. This technique is commonly called envelope encryption.