I think JA is deliberately misleading us here, but she is leaving a little space for a different intpretation. As others have pointed out, his reaction smacks of denial. He is still bitter and disappointed and that is effecting his judgement.

I have spent alot of time thinking about the phrase "wretchedly altered" and putting myself in Wentworth's shoes, I can see that he has perhaps romanticized and idealized Anne over the intervening years. This isn't that uncommon, people stay fixed in the mind's eye at a certain age and appearance, add to this a man at sea who in his isolation, must have tended to idolize Anne a bit. He had not even the benefit of a photo or picture to keep his memory grounded to some kind of reality. When suddenly met with the very real woman, one who had aged and suffered in the mean time, it isn't a suprise that he was almost repulsed by her and angry too. She not only destroyed his happiness, but also his idealized dream of what a woman should be.