Ok...so first off, let me say i know barebacking is by definition risky behavior and i probably didn't make the best choice believing the guy when he said he was "clean" in the heat of the moment. but the situation now is i ended up bb topping and cumming in a positive bottom, who later on i found out is positive, but has an "undetectable viral load" ... abt 54 he said. i've done a little research and the best i can come up with regarding the risk factor to me, as the top, of HIV infection is somwhere like 1 in 1600. my question to you while i freak out for the next 3 months (the window period) is if you have any information on how those odds change considering the bottom's "undetectable" (as far as i know) viral load AND, this is a kicker, if I ended up using HIS cum as lube for my dick in his ass. I've heard of a controversial study that claims that topping "undetecable" positive bottoms is "low risk" and also am not exactly sure what the tramissivity of various body fluids is. any insight would be much appreciated! Thanks!
You "know barebacking" is, by definition, risky behavior . . . ." Check!
You "probably didn't make the best choice believing the guy when he said he was clean . . . ." Check! Actually you can drop the "probably."
A viral load of 54 is not undetectable. It's 54! True, it's very low, but undetectable means it's below the level of detection of our assays.
Regarding the window period, yes, you'll need a test at three months. However, since you had a significant exposure to a guy who is confirmed to be HIV positive, the CDC recommends testing at both three and six months to confirm your negative status.
If your bottom boy had an undetectable HIV plasma viral load for six months and does not have a concurrent STD, the risk of HIV transmission would be significantly decreased. I can't provide you with exact statistics as to exactly how much decreased, as there are far too many variables involved with each sexual coupling: viral strain, host immune integrity, concurrent infections, trauma, etc.
Certainly the fact his viral load was low (but not undetectable) and you were the insertive rather than receptive partner would decrease overall risk. Using his cum lube, on the other hand, would increase your HIV-acquisition risk.
Had you sought attention immediately after this incident, PEP (post-exposure prophylaxis) would have been recommended. If it's been more than 72 hours since your Rambo-commando-Brokeback-Mountain sex-perience, this would no longer be an option.
I have no doubt you've learned a valuable (perhaps life-saving) lesson from this experience. I wish you luck for three- and six-month antibody tests that are negative.
I'm here if you need me, OK?