I am guardian over my 33 yr old daughter who is developmentally disabled. I am getting older and have trouble dealing with her on a daily basis.

First I would tell all family.
Second I would call Social Services to get a Social Worker, who can advise what your/her options are according to the programs of your state. Each state is different.
My state just had huge cutbacks a week ago, so there may be some confusion where you are for a while too.

Yes, since someone has to take over, either person, or perhaps they will need to go to a facility. I agree, involve other family and social services.