Welcome to the boards. It is okay to express yourself... We understand how hard it is. There is nothing really glamorous about care giving and it can be pretty rough some days.
I can understand how you feel being thrown into this. I think it would be good for you to get some more Christian counseling because it has helped you. I would venture to say that perhaps DH should go along with you... He does need to know that you are not okay with this and it's probably best to tell him in a neutral environment. Then, hopefully, you can work together for a solution and try to reserve any complaints for the counseling sessions.
There is some help available such as the Faith in Action Organization which might be an option for you. They may be of some help to get some of the responsibility off your shoulders. There website is: http://www.fianationalnetwork.org/. It is good to get the resentment out. We have all been there and it is a hard place to be. Meanwhile, just know we are here for you...