Tony Montana’s girl, Elvira Hancock, was somewhere between dirty and Diana. He even killed her former boyfriend in the process, who’d betrayed him. And to think it was like this at one point:

Their relationship eventually went sour, or rather, cocaine-numbed and she left him. That’s why you don’t break rule number 4:

Com could also be referring to Tony’s love of his actual sister, Gina, who he was very over-protective of.
Obligatory link to Future’s masterpiece, “Tony Montana.”