Welcome to the Forum and thanks for your confidence in our service, as well as your commitment to your own sexual health. I'll do my best to help. 

HIV risks.  There is clearly a hierarchy of risk for acquisition of HIV for sexual activity involving an untreated, HIV infected person.  For a male with other men as ex partners, the highest risk activity is unprotected receptive rectal intercourse where the risk for infection is about 1 infection for every 100 exposures on risk.  With unprotected insertive rectal intercourse the rate falls to about 1 infection, on average, per 1000 exposures.  Oral sex, giving or receiving is lower than that. The CDC lists for receptive oral sex and active oral sex as being "low" risk but do not provide a number.  In the past the CDC estimate was that performing oral sex on an infected partner led to infection in about 1 our of every 10,000 exposures and indeed, we are aware of occasional instances in which performing oral sex has led to infection.  OTOH, while I have to presume it is possible, neither of us on the Forum has ever seen or heard of a person acquiring HIV from receipt of oral sex. 

Two other important caveats related to sex with potentially HIV infected partners.  First, there appears to be virtually no risk for acquiring HIV through sex with an infected partner who is on effective HIV therapy and whose virus has become undetectable in the blood (only about half of persons on HIV therapy accomplish this).  Second and perhaps ever more important for you as you re-enter the dating scene is the pre-exposure prophylaxis (PrEP) with anti-HIV therapy is considered safe and reduces the risk for infection among persons having sex with HIV infected partners to virtually zero.  You may want to consider exploring PrEP with your own health care provider or a local HIV-prevention program.  I should emphasize however that PrEP does NOT prevent other STIs and for unprotected exposures, regular testing (most experts recommend every 6-12 months) for other STIs is important.

HSV.  Studies suggest that persons with HSV-2 infections are at somewhat (about 2-3-fold) increased risk for acquisition of HIV if exposed, even if lesions are not present.  The role of the location of HSV-2 infection is not clear but as you mention, oral HSV-2 infection is so very rare that I would not be too concerned. 

I hope that this information is helpful.  Stay safe. EWH

I believe that I provided you with numbers and an explanation to your question above.  FYI, your risk lifetime risk of being struck by lightening is about 1 in 10,000, the same as the CDC's prior estimate of getting HIV from performing oral sex on a person with untreated HIV.

As I said above, there is no doubt that persons have acquired HIV from performing oral sex on persons with HIV but it is rare, particularly when compared to participating in rectal intercourse.

Finally, I would encourage you to talk to prospective partners about their HIV status and when they were last tested for HIV.  You are correct that some persons might not tell the truth but my bias is that most people are honest when asked the question.

This is my 3rd response to your questions.  As per Forum guidelines, the thread will be closed in a few hours and there will be no further replies.  I hope the information I have provided is helpful.  EWH