、。
She got so furious at him she almost slapped him across the face.
Literal
She [topic-は] him [at-に] greatly belly [object-を] raised [because-ので], a-bit-more cheek [object-を] hit [almost-did-ところだった].
A two-clause cause-and-near-effect. 大いに ('greatly, considerably') intensifies the anger; ~ので marks reason. The second clause uses もう少しで~ところだった ('was about to X / almost X-ed') — もう少し ('a bit more') + で (extent) + ~ところだった ('was on the verge of, almost did'). The pattern reports actions that almost happened but didn't quite — a near miss. 頬をたたく ('slap the cheek') is the physical specific.