Welcome to HCM.
It is not true. Women with big asses are not having any relation to HIV
or any other infection. It is a total myth.
Similarly a rubber latex condom will not allow the virus to permeate outside and it offers a very high degree protection. If it is not true, all most all sex workers and almost more than 50% of men population would have already been infected with HIV. So have trust with condom.
Multiple partner sex and unprotected sex are always at risk.