Tell my parents im joining navy!?

im a 19 year femaile.. want to join navy.. i have no idea how to tell them what so ever! i really want to though!! like i talked to my recruiter and going friday again to talk to him.. however im so like like messed up because i want this and i know theyll be so mad! they wont support me or anything!! what do i do? i mean my bf is coming home soon and i was thinking of him tell them with me so its somewhat less tension but i dont know if itll wrk.. please help! i wanna sign next week, and leave in july!! :(