What if tomorrow never comes?

In the name of Allah, The Most Gracious, The Most Merciful
Assalamualaikum

Title: Will there be a tomorrow?

Each time an ustaz/ustazah ends a class with "wallahualam bi sawab, till we meet again next week insyaAllah", my heart would just sink because I am sooo afraid that I might not get the chance to live, to see through their next lesson.

Each time the imam for isya' prayers ends the prayer with the 2nd salam, tears would just well up in my eyes because I fear that it might be my last time, performing the isya' prayer ever.

Each time I step my feet out of the mosque, I feel at unease because I am so afraid that the next time I will be brought to the masjid, it will be the time when I die.

Each time I do my doa' to Allah, I feel so embarrassed with myself because with the great amount of sin that I have committed thus far, how could I still have the audacity to ask Him for forgiveness? Because sometimes, I find myself going back to my old ways and I would end up making the same mistake over, and over again.

What if tomorrow never comes? )':