My dad is unhappy with how much money I've been spending (again) and in his email he said "I want an explanation, by return, of how you intend to complete your degree."

Just how am I meant to answer that??? He added, "Failing that you can return home on sunday by bus and justify your bank statement."

I don't intend to go home tomorrow and justify the money I've spent. In my opinion, it's on stuff I thought deserved spending money on, and I feel kind of resentful that he just doesn't leave me alone about it. This is my money, that I've earned, and I have a part-time holiday job to replace it. But I don't know how to explain that in the email either, without him taking offence in some way. Already I know that whatever answer I write won't satisfy him in some way or another. It means that tomorrow I'm going to have to stay out all day grr in case he decides to visit me and have things explained further.