The other day when I dropped by my friend's place, it wasn't her who came to the door — it was her husband.
Literal
Other-day friend [gen-の] place [at-に] stop-by-[past-た] time, entrance [from-は] friend is-not-[and-で], that [gen-の] husband [subject-が] face [obj-を] showed.
立ち寄る ('to drop by, to stop in') is a compound verb — 立つ ('to stand') + 寄る ('to approach'). 玄関 ('entryway, front door area') is a specifically Japanese architectural feature where shoes are removed. 顔を出す ('to show one's face / to appear briefly') is a fixed idiom. The cleft structure 玄関からは友達でなく、その旦那が ('from the entrance, not friend, but her husband') places the contrast inside a marked topic-comment structure. 友達でなく is the formal contracted negative.