Ativan withdrawal - what to expect?

I've been on about 1mg of ativan per day for 3 weeks. It seems like if I don't take it I get very anxious and experience withdrawal symptoms that suck horribly. I have to stop anyway... how long can I expect wd symptoms for, how bad will they get, and what can help that I have? I have carbamazepine, benadryl, tylenol, aspirin, advil, and ritalin.