If We Were Cursed (en Inglés) - Lisa M. Sylvan

Bellamy Fray is convinced that detestable, suave Jules
Everidge and his occultist family are swindlers, exploiting desperate
people with their séances and curse-breaking. Preying
on people like Bellamy's own mother until she recently passed away.
Now, Bellamy will stop at nothing until she's proven that
the entire family are frauds.

Bellamy pretends to have a "curse" to infiltrate and expose the
Everidges. Yet as she and Jules work together to break it, Jules
is convinced that she is, in fact, quite cursed. Bellamy is certain
this is part of the con, but she swears she can sometimes
feel breath at her neck and an eye in a mirror watching her.
And she starts to question everything.

Her life-long friend Archie tries to help her through her grief,
but as Bellamy begins to spend more time with Jules she's caught
between the safe warmth of Archie, who has always cared for her,
and the wild, magnetic Jules, who may be the only one who can
save her.