Hi, @aykut, I know this is really causing you a great deal of stress but I think your friends and family are right. Quite honestly I’d try to forget about the incident. Tainted pins planted deliberately is more of an urban legend than fact.

Coming from a medical perspective, in most instances HIV can’t live outside the body very long. In a situation of a pin lying on a cushion for who knows how long, the odds of it being able to transmit the disease would be remote.

Syringes would be a different story because they are hollow and can contain blood serum and virus if used previously.
But this is a stainless steel dressmaker pin and it was clean when you examined it. Blood dries quickly on surfaces so there would have been some evidence of blood on the pin for you to see. I have some experience in blood born pathogens. I was the infection control coordinator in the dental practice where I worked for several decades. I am very confident when I tell you that the transmission of AIDS from this pin would be very remote. There is no need to be checked by a doctor.
So I hope you can exhale a sigh of relief and put this stressor behind you. 🙂