Conflicting information? Yes, but only if you're not selective in selecting websites. If you pay attention to the source and stick with professionally run and/or moderated websites, you won't find much conflict about the risks associated with oral sex. Those that fan the flames typically don't monitor or attempt to control the opinions of frightened people who don't understand the science involved.
Some experts indeed believe that the penile partner in oral sex is at no risk of acquring HIV. My (and Dr. Hook's) close colleague and friend Dr. Jeff Klausner, director of the San Francisco health department STD/HIV programs is one of them. The highest calculated risk, from CDC, is that such exposure carries 1 chance in 20,000 of catching HIV. My position, and Dr. Hook's, is that it doesn't matter; for all practical purposes, 1 in 20,000 is the same as zero. (It is equivalent to having a ** by an infected partner once a day for 55 years, and maybe never getting infected.)
Standard guidelines for PEP do not recommend it after insertive oral sex exposures. Even if you were to try, you probably could not find a provider willing to prescribe it. Certainly I would refuse if you came to my clinic, even if your partner said he has HIV -- and especially since he almost certainly isn't infected.
Finally, you make an excellent point that "some things just happen" despite all intentions of safe sex. That is why "do ask, do tell" -- i.e., routinely sharing HIV status BEFORE starting sex -- is a central component of safe sex among MSM. Oral probably doesn't make much difference, but what if "just happen" led to anal sex? I don't mean to lecture you, since you're intentions obviously are on the right track. But this is a lesson that other MSM readers of this forum can take home from your question.
In any case, stay safe -- and if you remain nervous about oral sex despite this response, feel free to use condoms for such events.
Regards-- HHH, MD
Generally it isn't necessary to test after specific exposures except those with particularly high risk, e.g., anonymous unprotected anal sex, sex with an HIV infected partner. All MSM and others at relatively high risk for HIV should just have routine testing from time to time -- probably once a year for you, as often as every 3 months for those at highest risk. If you haven't been tested recently, go ahead and do it now, since it's on your mind. But not because of the exposure you described.
As for other STDs, oral sex is also low risk; and most STDs acquired by oral sex (e.g., gonorrhea, NGU, herpes) cause obvious symptoms. But again, as a sexually active MSM, periodic testing for gonorrhea, chlamydia, and syphilis is a good idea.
Just to confirm -- testing necessary/unnecessary; if necessary, likely to be negative for HIV? I'm guessing testing is largely unnecessary, but might be indicated for peace of mind.
Also, risk of other STD exposures?