If you are over eighteen, then it isn't your mother's decision to tell you what to do. Many older adults are afraid of Facebook as they believe someone will access any and all financial accounts you may have, i.e., bank account, etc.
boyfriends and/or friends come and go, but sneaking around behind your mom's back will be a trust and respect issue that you may never get back. - if you EVER want to be allowed on Facebook, go on a date, go to the mall with your friends and NOT your parents, have a cell phone, etc. before you move out of home, then stay away from facebook. trust me, it is not that important. - one other thought, if your boyfriend is that jealous and controlling, that he would have you disobey your parents, RUN away!!! he is not the kind of boy you want, and he does not love you. check out the movie "fear" with reese whitherspoon and mark walburg, you will then understand what i am saying, but more importantly why your mom says no.
the legal age to use facebook is 18, but once you have reached the age of 16 you are no longer a minor and can do partially anything. If you are living underneath your mothers roof then you have no choice you must obide her rules. and there must be a reasonable exsplanation for this :D
listen to your mother and at the same time try to know why she ask you to leave facebook, also try to convinces her let you to use fb little bit a day and day after day if she trust you...she will never ask again
listen to her. i mean unless you have a really sneaky way to keep her from finding out like i do, just do what she says. its actually harder than it sounds to keep up with your friends on facebook and still pretend that you dont get on facebook. so just stay off of facebook until she lets you