AITA when I declined an inappropriate request from my girlfriend ?

Hi everyone! I was in my office to do my work and wrapping up for the evening when my phone rang, and it was my girlfriend. I haven't spoken to her in a while, so I was expecting some questions from her about why I didn't call her; however, she asked me for very disturbing things that require mature adults to do. It soon got to the point where I immediately hung up and privately messaged her that my car needed petrol; thus, I couldn't get service. But then she said she wanted to take our relationship to the furthest level and wanted to do the "it" process with me. That night was awful; I couldn't even sleep correctly. I took decisions into my own hands and decided to stop the relationship once and for all and blocked her. I had a promise with my mother that I wouldn't be very unnatural in front of girls.