Need your advice,please....

I'm a foreign graduate nurse and has been working in a rehab unit of a LTC center.This is my dilemma,from d time i started in the facility all i wanted is to do patient care esp treatment that's why i was glad to be in the rehab unit,however i was "transferred" to be d unit manager.I've been saying no until such time i didn't have an alibi anymore.I've been a UM for 6 months now and i am unhappy,I feel frustrated bec i am unable to finish my things to do since i'm doing charge,appt,family querries,wound rounds,care plans PPD/Flu/Pneumovax audit of all 40 residents,CNA complains among other things,i feel i'm endangering residents coz i'm unable to finish my "stuff".Thinking of going to work makes my back ache.I've been working at least 10 hrs a day just to be able to cope up w/the things d admin wants me to do and a day is just not enough.I go home only to sleep,last week i realized i only ate 2 meals d whole week,d worst part is i've forgotten that on my husband's bday i had a plan & asked for a vacation time w/c apparently was disregarded (i was in the sched even if d VL was granted).I submitted a resignation letter to my DON but i'm not sure if they'll grant it to me.Is there any legal implications if they said No & yet i refused to be UM anymore.I just don't feel i'm effective plus its affecting my relationship,my health and most imptly my residents.pls advice,i don't know what to say to my DON. . .