Studs was supposed to follow Lotts and learn what properties he wanted, so Bricks could get to them first. Instead, Lotts led Studs to the wrong place at the wrong time.
Faced with the facts, Cara admitted her affair with Bricks Bennett. She wanted Bricks, and she wanted the money, but there was Lotts in the way of both. That's where Studs Fedora came in.
Maybe Cara had drinks with Bricks Bennett...maybe more. Maybe Lotts walked in on them...or maybe he was supposed to. Maybe there was an argument, or some shoving..or maybe it was planned. But Cara was there when Lotts went out the window.