You have misunderstood something you read, or at least its implications. I'm also unclear about your sexual risks. Apparently you have receptive anal sex with other men, right? And since you ask about pre-ejaculate fluid (pre-cum) in your rectum, presumably without condoms?  If so, and assuming you have more than one partner, or a partner who has other partners, then you are at very high risk for HIV. However, the risk for any single exposure is only during the exposure itself. The idea that HIV might survive on or near the anus and result infection only later is absolutely wrong; I'm sure that never happens.

However, if you only have experienced anal fingering -- i.e. no penis in your rectum -- then you are at little or no risk for HIV. The virus is never transmitted by fingering, even if genital fluids are used for lubrication. Fingering cannot carry enough fluid with enough virus to result in HIV transmission. For infection to take hold, lots of virus must have contact with the kinds of cells that are susceptible to it. Even receiving anal sex with ejaculation in the rectum, with a known infected partner, the average chance of being infected is around 1%, i.e. once for every hundred events. 

Given your worries, it would make sense for you to be tested for HIV, especially if you have had actual anal sex, not just fingering. You can expect a negative test result.

I hope these comments are helpful. Let me know if anything isn't clear.

HHH, MD