<human>: Can you condense the text into three sentences or less?

Let me start off by saying, I love my bestfriend of 8 years to death. She's always been there for me. Last Saturday, everything was going as usual- we had left my place to head to a party, and we were singing in the car like the dorks we were. As soon as we got to the party, she started snapchatting someone quite a bit, not fully paying attention to what I was saying. I glanced over at her phone and saw that she was snapchatting my ex boyfriend.

My ex[M20] and I dated for almost 2 years, until last year, and I was completely devastated. I'm still not over him. And she knows that. Yet, the entire time she was talking to him right in front of me, and she was hiding it too. She noticed that I saw and immediately freaked out, saying stuff like, "I can delete him if you want", and, "I swear we aren't talking that much." Of course, I'm not going to tell my best friend who and who she cannot text, so I just smiled and said it was no problem. For the rest of the party, all I could think about was how maybe they were just study partners, perhaps, and that I was stupid for having my heart completely drop.

The next day was no different, she was just constantly snapchatting him and texting him in front of me. I was in the pool hanging out alone because she just wanted to talk to my ex, right in front of me. I started to get a little angry, but still, it shouldn't be something to worry about, right? 

Anyways, I don't really know what to do. It's not that I'm mad because I still love him- or whatever. I'm just really upset because she knows how terrible he was to me and how much he hurt me, and she was talking to him behind my back. It hurts, so bad. I feel so betrayed, Reddit. :( 

Please tell me if I'm wrong for being upset or not, and how I could possibly talk to her about this without sounding crazy. Thank you so much.
<bot>: bestfriend has been talking to my ex of almost 2 years behind my back, don't know how to talk to her about it and if I'm wrong for feeling betrayed