how can i talk to mom about this??

a few weeks ago my mom offered to get me on the pill. i've had a boyfriend for the past few months and she wants me to confide in her with stuff like this but talking to her about this kind of stuff make me nervous. i feel like she is going to tell my dad (who is insanely overprotective) and he's going to not let me go over my boyfriends house anymore. my mom says that she'll be cool about me telling her about this kind of thing but i know if i tell her i had sex with my boyfriend she's gonna flip. i have a feeling she want be as cool about this as she claims to be. i want to get on the pill for the benefits with your period and also for the whole "not getting pregnant" part lol. (i also have bad anxiety and it would just put my mind at ease to know there's a better chance of me not getting pregnant). being on the pill is something i want to do but i have no idea how to talk to my mom about this. please help!!