Why do you think it's an STD? No STD acts in this manner - no disease does, either. You don't transmit any viral hepatitis by just shaking hands, or by simple touch, nor do you transmit mono by a simple touch.
Could this be something psychological? I say that with no judgment, but if there were something that easy to transmit - by simple touch - we'd all be quite ill, right? That's not the case.
Your tests are all negative, except for EBV, and you are being treated for this. Have you shared your concerns with your doctor? You should do that, and let him explain how it's not possible for you to release toxins via touch. STDs don't work that way, nor do any other diseases. Let the Harvard educated doctor explain it to you. If that doesn't work, maybe it's time for some therapy.
I don't say that to be condescending. The mind can be really powerful and sometimes it's hard to overcome things we are convinced of.