Perhaps it is you who do not understand ad hominem; Your whole line of reasoning about a girl who may have been pregnant and aborted her child because I was "unworthy" is a proxy ad hominem, since the main point is that I was discussing that sex was safe and pregnancy chances are approaching infinitesimally small and you decided diverging the conversation from the statistical proof I've thus provided to a conjecture stating that I couldn't possibly know if I've impregnated a girl before and following with an attack on my character by asserting that she could've found me unworthy and thus would have aborted the pregnancy and not told me, you've attacked my character in an attempt to disprove my point.
Following the standard ad hominem definition of:
Person A makes claim X
There is something objectionable about Person A
Therefore claim X is false
I, person A, claim that I know I've not impregnated any woman.
You assert that since (obviously) you feel I would be found unworthy, that there is a chance she'd not tell me.
Thus I cannot possibly know that I have never impregnated a woman.
and following this you are also asserting that since I'm wrong here, my claims that protection are indeed safe, must also be false since I very well may have had an ex who aborted a pregnancy and never told me, thus the birth control methods used would have HAD to fail.
multiple spaghettified fallacies all throughout your argument. And yet nothing proved.