I don't see anything wrong with e-mailing the professor. Like awebb said, it would be a compliment in that you thought enough of her to apologize for not acknowleding her when she spoke to you. Also, you can just add that you are still depressed, and tell her you're scared of taking antidepressants.
I'd like to add that I'm on antidepressants and have been for probably 40 years! Can you believe that?

I'm clinically depressed, and without them I can't even function. There is nothing to be ashamed of or scared of. I thank God there is something like antidepressants for those of us who are depressed. Depression is an ILLNESS and is recognized by the American Medical Society as just that -- and Illness. It's also recognized by many other societies as an illness too, so it's nothing to be scoffed at. It can be very serious!
So please don't be scared. Just tell your doctor the facts - and I'm sure he'll understand and act accordingly.

But you should be treated. I wish you the very BEST. God bless you and please take care. Big hugs, Lee