I cannot reiterate how important it is to get a diagnoses whether it is Dementia, cancer or whatever, you are living with. It is not until you have that diagnoses that you can get the right support. Needs assessment. Attendance Allowance, hospital discharge assistance, and for the carer an annual health check, a carers assessment, a bi-annual grant, a be-friending sitting service, an Admiral Nurse's one to one support, or support from Dementia UK helpline, the list is endless. It also allows you to get your paperwork in order POA, wills, just in case bag, This is me, What if, living will, escalation health plan and again the list is endless. You only need to look at the Alzheimer's Society website or Dementia UK even Carers UK to see all the thing you should put in place and then benefit from as your loved one deteriorate. Memory Cafe are the place to go, everyone's in the same situation and no one judges each other regardless of their behaviour. The volunteers are well trained. your mother can get a be-friender or Social prescriber to go with her if you can go with your mum. Training and Carers peer support groups for you where you can offload and learn all you need to learn properly rather than relying on scant information from Social Services who are so very under staffed. You will have a council led Carers group too, if not sure ask your LA. You get a Carers ID card which allows you free entrance to most places when accompanied by your loved one. Blue Badge and so on if eligible.
Your mother is frightened, she realises she cannot make head or tail of her life now, no wonder she is depressed, Dementia is very frightening, even suspecting it is frightening more so than knowing you have it, but can lead a good life with it and knowing there is loads of help out there, you only need to know where to go. Read, read and read some more. I support 90 carers in my area and am a committee member of the Memory cafe as well, have been for 13 years. We help so many people to live a manageable life. Your mother deserves that too. I am so sorry you find yourself in this situation, Dementia is a challenging illness for sure, but with the right help it can be managed at home really well for a long time possibly to the very end.. good luck.