Livia decided she’d probed Sofia enough... and she’d found out things... not definite things, but she now had strong hunches. Firstly, Livia was certain there was a romantic involvement, as yet unresolved - the ring thing. Secondly, Sofia had almost certainly slept... and might still be sleeping with Tony. Livia was pretty certain he wasn’t the romantic interest... so Sofia was probably attending to Tony’s needs... for her ultimate gain.
That might mean she had ambitions to take over the business if anything happened to Tony.
If true, Sofia herself might be trying to use Livia and Marcia.
That wouldn’t do!