Hi Dave Palmer
really thoughtful responses so far
For me Jenniferpa has hit the problem on the head - we all make promises without understanding the implications - most we can keep anyway - but dementia is a whole other issue.
And actually, I think that's how you feel too:
'causes chaos' 'treat him like a human being' 'cost me my clients' 'trashed my business' 'made me promise' 'aged 15 years'
your own description is pretty loaded, isn't it.
There's no shame in realising the circumstances are just working against your 'promise' - and there's no doubt that you will always care about and supervise the care of your mum.
Then there's your mum's point of view. Canary has an important point - to your mum, sadly, your partner is a stranger. Worse - to her - he's a strange man in her home, he won't leave and he's being far too familiar with her (again HER view, I am not suggesting any impropriety). He will not have the baring of a professional carer, as for him she's his MIL - and that is confusing your mum. If she is calling the police, she doesn't feel safe and we all know that just being told a situation is fine doesn't mean we will believe it is - feelings are stronger than reason when fear, and dementia, sets in.
Maybe your mum would enjoy time at a day centre, so she is not at home every day - and any personal care and meal preparation might best be offered by having home carers visit. Contact your local SS/Adult Care to see if they can offer these. If she is self funding, she will pay, which offers the chance of you organising whatever care you think best.
You obviously care very much for your mum, but you are not expected to ruin your business and relationship.
best wishes