My sister gave me money as a gift to buy a motorbike, but now she wants it back and is threatening me.

I am looking for advice because I am going through a very stressful family situation and I don't know what the best legal or practical step is. A while ago, my sister gave me money to buy something that would help me financially. I decided to use the money to buy a motorbike because I needed reliable transport. She also gave money to my other siblings, and they used theirs for other things. At the time, there was no agreement that I had to repay the money or return anything. After I bought the bike, my sister became angry and started saying that she wants the bike back. She is now claiming that she wants me to return it, even though my understanding was that the money was a gift. The situation has escalated. She has:

Threatened me using different phone numbers Sent messages that I feel are intimidating.

Involved other people who have contacted me on her behalf.

Come to my area and spoken negatively about me to my landlord.

My main concern is not just the motorbike anymore, it is the harassment and threats. I am considering going to the police station to create a record, and possibly looking into a protection order if things continue. I would like advice from people who understand the law or have experienced something similar. What should I do first? report the threats to the police or go directly to court? If something was given as a gift, can the person later demand it back? What steps should I take to protect myself while trying to avoid making the family situation worse? I appreciate any advice. I am trying to handle this peacefully, but I also need to protect myself.