Most instructors would advise PB2 stoodents to be very wary about going out in stiff conditions which that was for your boat.
Also it was a bit of a bad day on Monday because the metoffice didn't quite get the forecast right and the wind was a bit stronger than anticipated and the waves were quite proper. We took the tug out of Langstone at about 14:00 and for the next 6 hours wished we hadn't bothered. So I think you are right those kind of conditions are on the limit of comfort and safety for a shorter boat
Did this happen at the Bar to Chichester harbour?
A good book is rough weather handling by Dag pyke
my advice to get good rough weather experience is to get out there and get it gradually building up from a 3 to a five. swap the missus for a more experienced person ( I am talking about boating not your marriage) so that you don't have to be overly concerned for your passenger during the learning process and then take the missus out and show her how clever you are.
Also try and fins somebody to buddy up with you with a slightly bigger boat but not much bigger
Hit this page and type in Dag Pike in the seach box
also there are two Aarticles by Paul glatzel in this section of the forum which might quench you thirst fo knowledge this evening