I have been living with my dad, his girlfriend of two years, and her daughter for a couple of months now, while my mom is visiting my sick grandfather in Sweden. I've only ever stayed at my dad's all weekend, so it's been hard getting used to living with his girlfriend and her kid full time. The kid is super whiny and pretty spoiled because girlfriend dozed on her, so I usually just stay in my room. Today, girlfriend was taking her daughter on a special outing because she passed a math test, and my dad suggested I go with them for a girls' day out. I wanted to say no, but I knew that he wanted me to get to know his girlfriend and girlfriend's daughter better, so I agreed. He gave girlfriend $300 to spend during the outing. We spent the day going in and out of the stores the girlfriend's daughter liked in the mall complex. Girlfriend ended up buying her a shit ton of clothes, makeup, and other stuff I don't remember. On our way back, girlfriend stopped at the Starbucks because her daughter wanted a drink and some cake pops. She ordered a drink for her and her daughter and two cake pops. I asked her if I could get something, and she said we ran out of money, and she'd get me something next time. When they got their order, I asked if I could have one of the cake pops, and girlfriend said that it was her daughter's treat for hard work and it would be wrong for me to take one, since I didn't do anything that deserved being rewarded. I'm not gonna lie, I was pretty upset. When we got back home, my dad saw their drinks and asked where I was. I told him that I wasn't allowed to get one because I don't deserve it. His girlfriend got upset and said I was twisting her words and the daughter just said I was being greedy and was jealous of her. I know I'm not entitled to a drink or a cake pop, but I also don't think it's wrong of me to be a little annoyed. Am I the asshole?

No, definitely you're not the asshole for telling your dad what really happened.