Honestly, she had a moment of weakness fukking with Floyd.
Reason I put the blame on her is because she KNEW TIP was unfaithful, ever since he popped on the scene (and Im sure well before). She had a moment where an equally or more famous guy, Floyd, made a move on her at a time when things weren't going so well in their relationship. She obliged.
I'm admittedly assuming some things here, but I'd wager a bet that Tiny knew of TIPs' ways very early on but was comfortable being the quintessential loyal dope boy wife because of his status, love and financial situation (as you've noted already). The relationship was on the fritz and what Tiny used to take on the chin, now makes her reach her boiling point.
I believe she fukked Floyd, partially because he said it - and some men look at other mens' women as conquest so he was more apt to brag and expose it than she would. The pictures made her look like a groupie, in my eyes. I honestly feel TIP in this situation and not because Im a man but because I hate it when people switch up their positions. I believe they operated their relationship in a way that isnt normal but she understood and rolled with it, eventually she got fed up and rebelled against it but the point remains that she was OKAY with it at first.
If she felt it was best to end things, then shes right.