Uhm okay

So as previously stated, I was at a Katy Perry concert with a friend and she actually wanted to go there because of Charli xcx because she is a huuuge fan. A day before she asked me if I wanted to go with her to a Charli xcx concert in Birmingham. She already looked up and the price for the flight, the concert and lodging would be 160€, so I was like okay but let's discuss it one more time. We discussed it on sunday and the price was higher than we first thought (185€) and I already said to her I have to rethink it. The best part is that she already bought the tickets without asking me. Yesterday I told her then that I don't want to come with her because in my opinion it's too much money for 2 1/2 days, and 1 day we will only be in front of the concert hall because she already said that she wants to wait all day there so she could be in the front row. So technically we would only have 1 1/2 days in Birmingham. In addition there are also costs we didn't calculated before like food, transfer from the airport and eventually bus or train if we want to see something in Birmingham. So at the end that would be at least 250€ if not more! And that for 1 1/2 day?! I told her yesterday that it's too much money for me and she was really understanding and said she will ask her mother to come with her. I still felt bad because she was really excited but I was relieved that she wasn't mad... Until this morning! I woke up to a text in which she said that I should've told her that earlier because her mother doesn't want to come with her and she already bought the tickets. Uhm what?! I never told I was completely sure to go with her so why did she bought them?? And now she wants me to feel bad so that I say: hey now that you have the tickets I HAVE to go with you!! I hate when people try to make me feel bad because it's very effective. Well, I talked to my parents and my dad said he would pay the trip for me. I was happy, because I could go with her! I told her that the situation changed and I could go with her. Her answer? 'I already asked someone else and he said yes.' Are you f-ing kidding me?? Why did you make me feel bad in the first place? I know that it wasn't right to keep her hopes up and then saying no but her behavior wasn't right as well.