Sadness and Grief: remember Allah and they will leave

Assalamu alaikum everyone

I am feeling sad today. Alhmadulillah, I am feeling very sad today. To begin with, the Almaghrib class I was taking ended yesterday and I was crying hard because a chance to learn about Allah has packed its bags and headed somewhere else. I am also sad because I got so confused, studied the wrong section for math, and flunked a quiz. It's worse than flunking, really. It's when you don't even get a number. It's below an F actually, propably in the Zs. I feel not so sad for myself as I feel sad that my Algebra 2 teacher might think Muslims are dumb or something. I was doing it for the sake of Islam and I failed myself, my parents, and now, Allah. How horrible could things get?

So I just opened up this book (Saheeh al-kalim al-tayyib for sheikh Al-albany) and it was the hadith of Umm Salama where when something bad happens to you and you say:

inna lillahi wa inna ilayhi raji3oon
allahumma ajir ly fi museebaty wa ukhluf ly khairan minah

I said it just once and I felt so happy suddenly and my heart stopped crying and I decided I have to spread the word. I am telling this to myelf, though of course I knew this before:

Islam works!
Islam really works!