I don't think anyone wants you to feel bad.
I think we can all sense that you already do! You poor thing. You're just doing your best like the rest of us.
First off I get rather cross with so called sleep clinics...they're a money making exercise and it sounds like you've not had much help from them anyway.
I would ditch them. Babies do all learn to sleep in the end.
I can only tell you my own experience...I'm single so have never had any help from a partner. What I have done is sleep with my children, in my bed, feeding on demand. For as long as it took.
My most stressful point was when my mother suggested I put ds1 in his own room, when he was 2/3 - which involved persuading him to stay there, getting up to his shouts several times a night, and total crippling exhaustion for us both.
I decided I wasn't up for it, having tried it, and he stayed in my bed till ds2 was born and ds1 started school and flounced off to his own bed, where he slept beautifully, because the baby was too noisy 
They have all slept really well next to me. That's all.
ds2 now self settles really well, I stopped bfing him when he was 4, which I never intended to do for so long but it helped him sleep so I just kept going. He just goes to bed and falls asleep now.
Maybe it is the lazy way, I don't know, but it has worked so well for us...I don't see the point in forcing the issue if it makes everyone so miserable.
I feel for you and hope you manage to find an answer, but do bear in mind that they all get there in the end, no training is necessary, you have to go with what works for you xxx