Idk how to feel about this... update

I'm 16 and bisexual. I recently got a girlfriend who is 26. 16 is legally age of consent in my state. We met online and my parents know about her. My mom is fine with it since I can't get pregnant. I spent the night at her house Friday and she let me drink. She invited her friends over and we played truth or dare and they kept daring me to drink because I have never drank alcohol before. Everyone else was drinking wine but they had me drink vodka. My girlfriend said it was because she wanted me to have a real first time drinking experience. They dared me to drink, take shots, chug half a bottle of rum. Idk if they drank any hard liquor at all because I was black out wasted. I remember seeing her fingering me. I couldn't move at all. She put something in me. I'm not sure if it was a dildo or what. I had told her I wanted to wait until we had been together a year before having sex. We have only been together 3 months. I also remember seeing one of her guy friends touching me and then he was inside me. I saw her sucking on his neck while he fucked me.

The next morning I asked her what exactly happened and she said I got drunk and passed out and they went to bed. When I told her what I remembered she said "Oh yeah we had a 3some". I was upset because I wanted to wait and didn't want to have sex and she said she was sorry and I was wet so she thought that meant I wanted to. She promised she would never hurt me on purpose and she loves me and she didn't mean to accidentally rape me. I'm at my grandmas rn and haven't responded to her texts today. The whole situation just makes me feel weird and I have this anxiety that goes through me when I think about it. I know it was an accident but it still makes me feel weird. If I can't get over it should I just break up with her?

Update: I went to over to my older brothers house to talk to him. He listened to everything and told me pretty much what you guys did. Plz don't be mad but I really don't want to go to the police.... I just don't feel comfortable doing that... My brother sent her a text and told her never to contact me again and blocked her on my phone.... He also bought me a plan B. I made him promise not to tell anyone and I really hope he keeps his promise...