I was relentlessly mocked by failure.

It's grammatically correct, but somewhat awkward. Reminder of what?" You might write ". . . the constant reminders of those failures . . . "

As written, there is no flaw.

To make matters worse, the constant reminder and bickering of those failures from my ‘friends’ and next of kin made me buckle under pressure.

To make matters worse, the constant reminder of those failures made me buckle under pressure.

Btw, the failures were reminded by them.
Which one sounds better??

How about this sentence?
It took me ten long years to finally settle my towering debts.
Flaws?

I have already told you what i thought would be a good way of writing this. I'm not here to be your always "on-call" copy editor.