You have a valid concern here.

If you are experiencing marriage counseling as a reinforcement of some belief that you're a burden, incompetent, less than, someone to put up with...I would definitely think that's something to take to sessions with your husband. Maybe your therapist can help you frame how you present it so that you're sure to get the message across that you are under a great deal of stress as the parent of a child with a disability. It's not a you thing. It's not a daughter thing. It's a recognized life thing--a huge stress. (In fact, you might want to google Parent to Parent and see if there's a chapter near you. Where I live, they pair young parents with other parents who have a child with a similar disability who are a little further along the road, and they provide emotional support and connection as well).

I agree with atisket that it would be good for your husband to experience 5 days without help from you in caring for your daughter. It might be eye opening.

Anyway, I just wanted to say that you have a valid concern. On a deeper level, all of this is mirroring a belief you have about yourself that's not serving you at all. I've found in my own life that others are more than happy to accommodate my own negative view of myself. It works out pretty well for them, in fact. So, it's a two sided thing. They can't buy into you as the bad person if you don't promote yourself that way. But first, you have to believe that it's a false idea before anyone else will follow suit. Some never will. But that can't be your issue.