Upon reflexion it was really bad ; swimming OUT into the waves was easier because I could dive into them, plus I was not tired yet, but coming back tired with them pushing me under over and over was completely different. Even worse is I have little body fat so I have to work to stay a-float so when each wave crashed on me I had difficulty telling which way was back up to air till the water settled, and the next wave pushed me under again. But I forced myself to stay calm rather than panic (as I was thinking of death) and burn my energy that way.
As a surfer since 1966 I can confidently say that the way to swim in through large waves is to roll yourself up into a cannonball and let the wave wash you in with it. As soon as you feel it release grab air and take as many strokes in as you can before the next wave, then curl up again. The strokes between waves do not have to be hard, digging strokes, I usually side stroke to conserve energy and keep an eye on the coming wave.