pollomoomin I can completely identify with your first paragraph. There is nothing quite like feeling a total failure at BFing to tip you over the edge into PND. The peer pressure and the pressure from HCPs to do it and to be able to do it easily is immense. And the guilt attached to stopping because people will judge you as lazy/shallow/selfish/vain is overwhelming.
I can honestly say the day I came to terms with the fact that I could not continue with BFing with DC1 and DC3 (I was only three weeks in with both) felt like the most enormous black cloud had been lifted from me, and I never looked back. I literally changed overnight and I was a better mother for it, without a doubt. Better than I would have been by martyring on and giving them the benefits of breast milk, but being abjectly miserable and in pain. But that's me. I am genuinely delighted for anyone who finds it easy and if I had a fourth child I would still try my best to BF, but not a single tear would be shed if I failed and bailed next time. I am so over that.
Where I will get a bit judgey is when women will struggle on for months and months, miserable, feeling useless and hopeless, not enjoying motherhood at all, stressing about lack of sleep, or the baby's low weight, frustrated at the sheer number of hours given over to feeding, frustrated that in spite of those hours the baby never seems full or content for more than an hour or two and yet……mummy won't even consider putting some formula in a bottle and cutting herself some slack after three or four months, because she wants to do everything 'properly'. And by the time baby is ten months old and still hasn't slept through the night she's on the verge of a nervous breakdown. 
I just don't get it.
I know that BFing counsellors and advocates have a solution to just about every classic BFing problem there is, but some of those so called 'solutions' are extremely complicated and labour intensive in themselves and can involve weeks of trying to establish different patterns, routines, methods, schedules, and then we are told 'it won't necessarily happen overnight, you need to keep trying this, and then trying that…..' meanwhile a few more weeks of confusion and misery have passed. And you are told 'you must be doing something wrong, its so easy and so natural providing you just listen and do it right….'
'It's hurting? That's because he's not latching on properly. Here, let me look Oh. He is latching on properly. It must be you. You are sitting all wrong. Sit up, lay back, lean to the left, hang upside down. It's important to feed from both breasts at similar intervals or you'll get mastitis, except if you get mastitis anyway in which case it's ok to just feed from one for a while, but it's better to just feed through the mastitis. Lay him this way and if that hurts then lay him that way and if it still hurts just feed through it, it will stop soon. What? It hasn't stopped? Your nipples still look like chopped liver? Oh. Never mind. Feed through it. You've been going for an hour and he's still hungry? He's only had foremilk. He needs hind milk. After x number of minutes the fore milk will be finished and the hindmilk will kick in. Keep an egg timer with you. Feed him for longer. Stop him feeding, he's just comfort sucking now. Let him comfort suck, he's distressed. He's crying after his feed? He's probably overfed. You gave him too much. You should have stopped sooner. He's not hungry he's just thirsty, FFS woman, can't you tell the difference? Oh hang on he's not thirsty or hungry now, he's bored, or he's tired or he's feeling insecure. Just feed him for that too….basically the answer to everything, including excruciating pain, is to just keep feeding through it. In fact, never leave your sofa. Let your other children play with matches or the traffic but just keep feeding. Not enough milk? Rubbish, of course there's milk. No-one has no milk. That's a myth bandied about by silly women who won't try hard enough. Oh. There's not enough milk. OK, next time you have spare milk, express it and freeze it so when you have no milk in your boob you have some expressed milk to hand. But how do I do that when I feel like I barely get a gap between actual feeds and as soon as I have milk the baby wants to drink it all and then there is no milk again? Besides, that breast pump feels like torture. Try a different breast pump. Buy these nipple shields, buy these pads, buy this cream, buy cabbages, drink more, drink less, eat this, don't eat that. Your baby doesn't sleep thought the night or for more than a hour at a time in the day? So when he's asleep wake him up and feed him so that later, when you are asleep he won't wake you up for a feed. What? Wake him up when he's asleep? I only managed to put him down an hour ago, after feeding him for an hour and a half. If I have to wake him up now I might kill myself.
And on it goes. But apparently it's the easiest most natural thing in the world. If only we'd listen to the people who find it easy.