Charging a sublet fee when it is not sublease?

[S Lane]

Hi all-

First time user here. I did a brief search on the forum but did not find any discussion pertaining to my specific situation. If my post is redundant or overlaps with another posting, please let me know or merge the conversation.

I have some issues with my landlord and would love some feedback. I am living in an apartment rental and my current lease runs out on March 31st. I recently bought a house and a friend from graduate school agreed to take over my lease from Jan to March 2018. After speaking with the property manager, she confirmed subletting is allowed and she would charge me $20 to process his application. The apartment would be still under my name, and my friend will be listed as an occupant. Any damages or problems caused by him would be my liability. Seemed reasonable to me.

Today, my friend called me and let me know that, after running his credit history (credit score 790+) and references, the property manager decided to start a new lease with him. She pushed hard for him to sign a 16-month lease. After my friend declined, she offered him a 6-month lease. She said she would just start a new lease with him, and cut my lease. My friend agreed but he decided to make sure that I am okay with it before he signs anything.

I thought it was atypical, but I can't blame the property manager tries to lock down a good tenant. I called the property manager and she basically confirmed what my friend told me. She said since my friend's tentative lease starts on Jan 12th, she would charge me a prorated January rent. I thought that was fair. Then she said, "as I mentioned before, you would also need to pay $150 to process the sublease. Now, I have a problem with that. 

1. She never mentioned the $150 administration fee before. Not in the lease, not in any phone conversations, not in anywhere in writing. Still, she said "as I mentioned before," as if it was something I was aware of and consented. 

2. If she is breaking my lease to start a lease with my friend, why is this sublease? He is not taking over my lease. She is starting a new lease with him.

3. This whole thing just left a sour taste in my mouth. She seemed to want to squeeze every penny out of me. First, after learning my friend's excellent credit score and amazing references, she immediately pushed him to start a lease with her. This all happened without me knowing. Then, she wants to charge a mysterious fee for subletting when there is not sublease generated. 

 What are my options? Can I refuse to pay the fee? Any insight would be greatly appreciated!