If you really want to dig into the science got to a medical school library, or a good university library, and look into scientific reference material. You can get access to anything doctors read if you really want to. But you're going to find out that the answer has been provided to you, that in theory the virus exists and in the early days of HIV docs did worry it could pass through oral, but in all these years nobody has ever gotten it solely by engaging in oral sex. As you have been told, if you keep obsessing over it that won't make your life any better, so you might turn your attention to that part of you and work on that. Peace.
Your question was answered last time that HIV is only transmitted by unprotected vaginal or anal penetrating sex or sharing IV drug needles. Air and saliva inactivate the virus. Doctors that have worked with our site that are experts in the field of HIV as well as expert opinion in general guide this answer.