I am so very sorry that you are going nutz over this one comment. Maybe I can help though. I used to be a paramedic, and one of the most important things was to keep the patient calm,,, not by outright lying to them, but just to be reassuring.
Also, in my hundreds of doctor's visits, hospital stays, etc., I have noticed that almost all medical personnel do the exact same thing. If the patient seems stressed or concerned, they try to reassure them, and try to show empathy. I have even heard comments made to patients from doctor's receptionists. They absolutely should not be commenting about anything. And, most times, the technicians or lab folks, should never comment either. I believe that what happened to you, may have just been the lab person trying to show empathy to your statement.
I do feel secure that you can trust what the doctor/manager said.
Regarding the anti-depressant, again, the lab tech is NOT a doctor, and should not have given her opinion on any medication or diagnosis. If you are depressed and cannot shake it, then go to your primary physician, and talk to him/her about your depression.
I hope so much that this helps you! My very best to you!