Carol,
First off, don't beat yourself up over this. You are not alone - there is support out there for you and the countless others who are travelling down this same road.
I would suggest talking to a Geriatric Care Manager (http://caremanager.findlocation.com) for advice or guidance on how to move forward. Depending on where you live, there might be various care and living options and arrangements - nursing homes, assisted living facilities, adult day care, in-home respite care to give you a break, etc. It is possible that your mother could qualify for assistance if her finances become depleted - Medicaid, or the VA has an underused and poorly marketed program - Aid & Attendance. The great counselors at A Place for Mom would be more than happy to assist as well.
Have a third party facilitate a conversation so that you are certain you are respecting her wishes and providing the most appropriate care and living arrangement, and that you are taking care of yourself as well.