lee is correct. a weaning off schedule is a must. i stopped taking a benzo abruptly and had a grand mal seizure. drugs of this class-benzo's-have a half life in your body occuring after you have taken them for a while-usually after 6 months-so it's necessary for your doc to help you.
also sounds like you have an adverse reaction to ativan anyway. that's why you are having those symptoms u mentioned.
don't think you need to go to a rehab, just need a weaning timeline to get you off.