Hey there man, former member of this site and it's been a while, wanted to chime in!
I struggled with pornography from age 12 to... jeez what 18 or 19. And let me tell you something, it's quite the dragon to slay. You were smart, you knew what you were doing was wrong and caught yourself. That's a hard thing to do, and to be so humble and honest about it is hard to do.
I've been married for a year and boy, sex is important in the strangest ways. I understand why you did what you did while your wife was pregnant. Doesn't make it right, but biologically it makes sense. You are doing all you can to dominate that problem and I really don't see any issue in your approach.
I think your wife has something deeper than the surface biting at her. Depression after having a kid can last YEARS, and to be honest it may be more that than your short stint with porn... As a human, I know how it feels to feel inadequate and tired and overwhelmed. As a woman, I know how it feels to stack hormones on that pile.
Just keep loving her. And be straightforward. Express concern for her needs and see if maybe you can get her to open up in a positive way rather than in this "I'll never forgive you" manner... And definitely meet with the bishop alone and tell him that she is treating you this way... Man I can't imagine doing that to my husband when he slips up on things. It isn't fair to you, and it certainly isn't good for her either.
Express concern to her family as well. If they know the situation, try to show your point of view and your love for your wife and your fear for her attitude. Something could be a lot more wrong under the skin than what you did. Counseling, therapy, visiting that bishop, and prayer, do it all man. Being young sucks, and being married can be complicated! But what I've learned in the past year? It can be done, all of it!
