Scary for sure, but you and your wife doing everything absolutely correct and quickly...is probably the reason she's doing as well as she is.
21 years ago, my buddy and I were walking toward the 18th green of the course we were playing (walking) and he saw a guy drop on the 17th fairway (also walking)...which was parallel to ours.
By the time I ran over there, my buddy was already doing CPR.
I had my work cell (one of the first people at my company because of my position and didn't even have a personal one at that time) and called 911, then we traded off on the compression's.
What I thought were breaths (deep gurgling) when we pushed...really weren't.
Although the ambulance was able to drive right to us within about 15 minutes, the EMT's pronounced him deceased...while we were just standing there in shock.
Something you never forget.