Atenolol and anxiety

I am trying to wean off of Atenolol bc it makes me tired and I feel as though my metabolism has slowed down. I have been on it for one year due to a fast heart beat. I did not have hbp when prescribed and I don't now. I was suffering from anxiety due to katrina and quit smoking. sometimes I feel sick to my stomach. has anyone gotten sick to their stomach from this med. also, I found that if I take it at night I am not tired during the day but I do have strange dreams.
my real question is how can I wean myself off this drug. I am afraid that if I stop it I will be somewhere and my heart will jump out of my chest.

I have been on atenolol for 19 years. I think it effected my thyroid. I was on it for 7 yrs, was tired and cold all the time. Was put on thyroid medicine. I am still cold all the time, read on-line that atenolol slows down blood flow to hands and feet and can cause coldness. Also having hair loss and anxiety. It appears that the atenolol affected my thryoid, the thryoid medicine causes the anxiety - and the cycle continues!