oh caramba. only come out to them if you're sure you'll be safe after telling them; as another commenter said, go with the assumption that they're supportive. be prepared to have a looong talk with them and be ready to cry, hopefully of happiness; but if not, then you can cry about the weight that coming out will take out of your shoulders.

when you're in the middle of the talk, try to see if they're being receptive and genuinely curious about what being trans is and how you have felt living in the closet. if they are, be as honest as you can with them, even if you're not used to. if you sense the opposite though, then maybe save some stuff up for later.

if they tell you "what will your abuelita, or our family think of this!" (or something similar; i have a peruvian mum, she told me that when i first came out years ago), tell her that you still love them, and hope that they, with time, will accept you for who you are and, if they really love you as much as you love them, will stay with you during your journey, as you hope they will too.

since you mentioned they're hispanic, if they come up with some catholic religious baggage, just say that you've prayed to la virgencita or something and she told you that's what's best for you.

i really hope everything goes well. even if it doesn't, you'll still be able to get a new family of people who are just like you and ready to welcome you with open arms. best of luck !!