In my uninformed opinion (I'm not a health professional), you should have the Q-TB Gold test done to confirm your latent TB before starting on 9 months of isoniazid. I think doctors in the US have a protocol they must follow to keep TB from spreading, so they often suggest just chugging away on 9 months of liver-damaging drugs without first doing one more precautionary test to confirm. I just had a positive PPD although in Europe the guidelines are different and would have judged my PPD negative b/c I have no risk factors. My chest x-ray was clear. I then waited three weeks after the skin test to do the blood test (Q-TB Gold), which turned out to be negative. Perhaps some of us have sensitive skin and react to fixatives in the PPD fluid?
As for your friend with AIDS (which I'm sorry to hear about), if he was symptomatic (coughing) and TB positive, I think the hospital would have forewarned you, don't you think? Especially if your daughter was visiting him.
Even if you have latent TB, there are cures for it. Google rifampin and check out the latest studies on its efficacy. It's only a four month regimen. You have options.
Good luck and don't freak out!