What's the difference between Citalopram and Ativan?

I tried Citalopram a while back, only one pill and I ended up in the hospital. My dentist is wanting to give me Ativan to help with my anxiety but I'm not sure if they're in the same drug category and a little worried I may end up in the hospital again.

: http://alcoholdrugstreatment.info/whats-the-difference-between-citalopram-and-ativan