Definition: Given a real-life anecdote of a complex ethical situation, generate a suitable title that describes the main event/root cause of the situation. Imagine that the given text is a social media post, and you have to write the title of the post, so the users can decide to read the main text or not.
Input: This is a past incident but I am curious what you all think about it. This is high school.

So I was very much a quiet follower type raised in an upper middle class family. I had two best friends, queen bees who I will call S and L. L is in the same economic bracket but stingy. She rarely paid for anything. S was lower middle class bordering poor. She didn't have a lot of funds to spend. 

Now every week there was a multicultural food event where we had a large variety of desserts, food and etc. I usually pitched in for buying food since I like food and it had cheap multi food deals. 

But this time I wanted to save money. I had no plans to really buy anything. I tell S this and she blows up. Saying I owed her for all the times she shared her lunch box cheese with me when we walked home. 

Incidentally she said she didn't like it and she had to finish her lunch boxes or her parents would yell at her. So it wasn't taking food from her but giving me the discards while she ate the crackers and meat part of this premade food.  

I yelled back this and how I didn't owe her anything. I stomped off and she proceeded to not be friends with me anymore. My other friend, L, told me I should just apologize to keep the peace and that I should have paid since it wasn't a big deal. 

I felt used though and like S took me for granted at that moment. So I didn't apologize. But because of L's words and the fact I do think S would have forgave me if I apologized. If I simply bought the food for S....

AITA for not buying S that food and yelling back at her? Bonus question. Should I have apologized to her?

not buying my ex-friend food which ended up breaking up the friend group