Firstly I think she didn't done the right thing. Because she insisted you to make the promise. In friendship I try to avoid financial issues. Secondly you why you made the promise and didn't fulfilled it. So I think you broke your promise and it was not right also.
You are right brother, both if us are at fault but mine seem to be even worse because I promised, when I know it was beyond my power to fulfil..
Thanks for reading mate❤️