how do i tell my family & boyfriend that i'm bisexual?

[_nini]

my mom seems to be disgusted by it.
my dad thinks its wrong
my sister thinks is weird.
i asked my boyfriend what he would do/say if i told him that i was bi..and he said that he wouldn't trust me.

i don't see anything wrong with it.
however,
i don't want to keep it to myself.

i'm hesitant because everyone seems to feel some kind of hatred toward bisexuals.