Since you've been clearly told that HIV is not a reality for your situation, you need to talk to your medical care team about treating the anxiety. How anxiety is treated is based on the individual and depends on things such as how much the anxiety is impacting your day to day life. Some can control their anxiety through use of coping skills and lifestyle things. That would include meditation, mindfully distracting yourself, deep breathing, regular exercise, healthy diet, good sleep, etc. Some will need to do psychotherapy or talk therapy where they receive treatment such as cognitive behavioral therapy. And some will benefit from medication along with that psychotherapy prescribed by an MD or nurse practitioner. Your problem and disease is not HIV, it's anxiety. Anxiety is also a medical condition and it is treatable. So, go get treatment.