thats when everything fell apart

The second book of a book that is no longer available but the first chapter explains a lot. Destiny is a family girl. She has had a lot of problems in her life and lately, there's been more and more. Her boyfriend Zayn is amazing but there's a twist. Someone else is in the relationship as well who is it? Why is destiny so close to her friend Kaili? What happens between them? I guess you have to read to find out...