My girlfriend (24f) wants to break up cause I (26m) bought the wrong chocolate

So yesterday my girlfriend went to a friends house to do some sewing stuff (they're both into cosplay and such) and she was in a very shitty mood. Tired, hungry, sunburnt and just overall in a bad mood. On her way back she messaged me saying she wanted to eat something from this one chocolate shop (they make their own chocolate and she loves it) and it should be open. She wanted me to pick her up some chocolate and take it to her at her friends place and she listed 3 different kinds of chocolate she wanted and what percentage of each type of chocolate she wanted. (She's kind of a chocolate snob)<br><br>She wanted 70% milk chocolate, 60% dark chocolate and 50% white chocolate. I am not good at remembering these numbers and it's sometimes hard for me to understand her, but I wrote it down to make sure I wouldnt forget. Unfortunately the chocolate shop was closed and they had a sign saying they'll be closed for the rest of the day/week. So I went to the nearest supermarket to get her chocolate and this place has really good chocolate and they have it in the percentages she wanted. Problem was they didn't have 50% white chocolate in the 100g bars, but they had a 200g bar of 40% which i thought would be fine. Then I took the chocolate to her friends place. She was very happy and I could tell the mood had lifted a bit at their place, until she saw the chocolate. She asked me "Why is this 40% and not 50%?" And I explained how they didnt have 50% in the 100g bars, but they had a 200g bar in 40%. Then she just started scolding and berating me for buying the wrong chocolate, even though she knows I'm not good with these kinds of numbers. Some of her friends started defending me, but she just said I constantly fuck up the simplest things and I'm too fucking stupid to be her boyfriend and that she wants to break up. I was crying a little and tried to explain how I'm really bad at remembering these numbers, but to no avail. After she calmed down a bit and stopped yelling at me she said we should talk in the morning after she's had a good nights sleep. So now I'm lying in bed crying and writing this in the middle of the night because I don't know what else to do. Should I go buy the correct chocolate? I'm really lost for what to do<br><br>TLDR: my girlfriend wants to break up with me because I got the wrong percentage of white chocolate