Hugs to you. I give you credit for having the courage to admit this. I'm sorry you felt you would create a backlash - no decent person would criticize you for voicing these feelings. If you get any negative responses, ignore them - don't even read to the end of the post!
It's a myth that we're supposed to love every aspect of motherhood. And loving our children is very different from feeling up to the task of managing them all the time, especially if they have a chronic illness or a disability. These are huge stressors and things that aren't always supported by our larger community or family. It's relentless.
I was diagnosed with depression a few years after my child was born, but I learned that I had been suffering from it for decades. The stress of motherhood (and maybe the hormones too) exacerbated it. I got help for it, and it was a relief to learn that I wasn't a defective human being or lacking in some basic nurturing components. I too wanted to run away.
I did have a supportive husband, and I think it would help you if your husband could get on board (perhaps in talking with one of the counselors) so he understands that you aren't "just in a bad mood" or whatever. I wound up working out a few days "off" per month with my husband - I wanted to get out of the house during the week (not just on weekends when everyone else was out there). We scheduled them a little bit around his schedule, but once they were on the calendar, they stayed there. I was helped by just knowing I would have my own time, when I wouldn't be called for anything (not planning a meal, not letting someone know where to find something, blah blah). Originally I did errands and such, and then I said, "Wait, this is supposed to be MY time!" So I did things like go to movies, take myself out to lunch, try on clothes, browse for fun things, and so on - ME time.
But that's just an example - do what works for you. I commend you for seeking counseling - if you want to pick the counselor you feel the best connection with, great. Stick with it. You started to get a better handle on things, but then you had a set-back. That happens. Be sure that your counseling isn't just devoted to finding answers to your parenting stresses - those books can help, but be sure to take time for YOU the woman, YOU the person, and not just YOU the mother or wife.
So - you are NOT a failure. You are going through a tough time. You've given voice to it, you've sought help from counselors, you've sought support from Mamapedia. Its not going to be an overnight turnaround, but you have taken the first steps in a journey. You should be proud of yourself. If it's necessary (and it probably is) to get your husband involved, please do so. It's important that no one blame or shame anyone here. It's not entirely your problem though - if you have a problem, he does too. And maybe some things he does or says are having an effect on your problem.
I was able to beat my depression with counseling, the use of medication for some time (weaned off them now), and with things like exercise and nutritional supplementation. But it's not just a simple thing like "go take a walk" or "join a gym" or "take a vitamin." Those things don't work alone, and they can be overwhelmingly difficult steps when you're already so incapacitated that you just want to run away. Sometimes for me, getting to counseling and sorting the mail were the only successes of the day. Sometimes I measured in terms of what didn't happen - "Okay, my kid is alive and halfway fed, and the house isn't on fire. It's a good day."
Give yourself those gifts. You deserve them. Let me know if it would help to chat privately as well.