When is it okay?

When is it okay to be angry?

In the Bible, we learn that we should let God be the judge and that we should always trust Him for provision.

Imagine you're in this situation: Someone borrowed a large sum of money and hasn't paid you back. Because of that, you are now broke $ What makes it worse is that the borrower is still going out and having fun while you are stinging and wondering how you're gonna pay for your next meal. So then, is it okay to be angry at the person? I mean you technically are not broke but you're "suffering" because of someone else. Being angry at the person is only natural but then you look back and realize that despite the day to day struggle, God has been providing you with just enough for every day, no doubt tight, but still provision anyhow.

So then again, you ask yourself, is it okay to be angry? 

I mean you still have enough for each day.

Isn't that enough to be thankful for?