I agree on your stance against the way emotions can negatively affect someone. but in this case situations where i would let them in cause more happiness (joy) than sadness. its a good feeling, so i think its alright.
http://plato.stanford.edu/entries/spinoza-psychological/
from Spinoza:
Finally,
active joy and
active desire
which Spinoza introduces at IIIp58 represent a separate class of
affects notable both for their novelty against the background of
traditional accounts of the passions and also for their importance to
Spinoza's ethical arguments of Parts IV and V. On traditional accounts
of the passions, even Descartes's (
The Passions of the Soul,
I.1), actions and passions are the same thing, regarded from different
perspectives: when A does X to B, X is an action for A but a passion
for B. For Spinoza, however, anything which follows in a person where
that person is an “inadequate” or partial cause of the thing, is a
passion, and anything that follows where a person is an “adequate” or
total cause of the thing is an action. Thus Spinoza's class of active
affects places a strong emphasis on people's roles as total causes of
what they do; because it becomes for Spinoza ethically important that a
person be active rather than passive, that emphasis raises a host of
questions about the extent to which a person, a particular thing
interacting constantly with other things and indeed requiring some of
them for sustenance, can come to resist passion and guide himself by
means of joy and the active desires.
Because joy and sadness as introduced at IIIp11s are passions, all
of the desires arising from them or species of them are passive as
well, that is, they are not desires which arise from a person's
striving alone but only as a partial cause in combination with other,
ultimately external causes. Active joy, which must include at least
some types of warranted self-esteem, and active desires, among which
Spinoza lists at IIIp59s tenacity (animositas) and nobility
(generositas) are wholly active however; that is, they are
emotions and desires that people have only insofar as they are adequate
causes, or genuine actors. (Notice that sadness cannot ever be an
active emotion. People cannot, insofar as they are active bring it
about that their power of acting is decreased, so passive sadness,
unlike passive joy and desire, has no active counterpart.)
