Some parents are told they have to die before their adult children qualify for housing, and many young people end up being warehoused in long-term care homes with no one in their age group and no programs for them, said Martha Fox of Dundas, Ont.
"We were told when Matthew was 18 that in order for him to get housing support, a residential home, a community home, that both George and I would have to pass away, and that Matthew would be placed somewhere," said Fox.
"A placement like that would mean the loss of his job, his day program, his friends, his peers, his special Olympics activities, his volunteer position with the (McMaster University) men's basketball team. In fact it would mean the end of his life."
There are thousands of families across Ontario "in the same boat," added Fox.
"We've talked to families all over the province, thousands and thousands who are terrified, and some say 'I hope my child dies before I do because I can't even imagine what’s going to happen when I'm not here,'" she said. "That is terrifying, that is the stuff of nightmares, and that is what we are all dealing with."
Some parents in their 80s are still caring for developmentally challenged adult children who are in their 40s or 50s, and half of them are single-parent households, said Fox, who met Thursday with Progressive Conservative Leader Tim Hudak.
Ontario is justifiably proud of closing the big institutions where it used to house people with developmental challenges, said Hudak, but the province must do more to make sure there are necessary supports in the community.
"You can judge the success of a society by how it treats its most vulnerable populations, and sadly in 2013 we're failing that test," said Hudak. "We can do a lot better."
The Opposition accused the Liberal government of dragging its feet on setting up a committee, which it twice voted to support, to find ways to help people with developmental disabilities who are looking for housing.
"There are over 15,000 people in this province right now who are waiting for appropriate housing," said Deputy PC Leader Christine Elliott.
"Their parents are frightened and desperate. They have no idea what's going to happen to their children when they're gone."
In an emotional speech in the legislature, Elliott said if politicians can't do some basic work to help families facing such uncertain futures for their children, "then I think we all have to ask ourselves, why are we even here?"
Fox and other families created the Dundas Living Centre and are looking to set up an alternate home for Matthew, 32, and others in his age group on the third floor of a convent in Hamilton.
There are too many other families without anywhere to turn, added Fox.
"We're looking at creating a community home where these young folks can live with their peers, with their friends, who really have been to a great extent their family and their communities for years and years," she said.
Community and Social Services Minister Ted McMeekin said families must wait their turn, follow the government's rules and be evaluated and assessed before being added to the huge waiting list for housing.
"People can't simply jump the queue because they have an outside the box idea," said McMeekin.
"We have a process in place ... that requires governmental services assessments so everything is fair and equal and priorities around residential payments, particularly in a climate of scarce resources, are made contingent on greatest needs."