It was my friends birthday yesterday, the night before, she rang me crying saying she had thrown her boyfriend out because he hadn't helped her children to buy her a present (with her money) there's more to it but that was the last straw, and she felt dreadful because her children were upset that they had nothing to give her in the morning. Fast forward an hour I got out of bed, dressed, drove to asda and bought a few bits so her children had something to give her in the morning.
Thanks if you've got this far there's more 
Anyway she was so grateful sent me a really lovely message about how I'm such a kind person and she's lucky to have a friend like me bla bla.
Fast forward to last night, I went to her house for a few drinks, we were all pissed, having a laugh and something in her head switched or I don't even know what happened, I've still not got my head round it. She just started shouting at me, asking why it was my business why she had done something, I told her I actually didn't care why she had done "it" I was just making conversation.
What would you do? Do I let it slip and put it down to the drink or do I say something?
I just feel like she's thrown my kindness back in my face, I'm questioning why I bothered and is she a friend?
She is 49 I know age is only a number but I'd of expected this sort of behaviour from a teenager