Okay so MIL isn't elderly but I wasn't sure where to post this, I need kind advice rather than the blunt AIBU threads. 😂
I live with DH, I'm physically disabled, my eldest son has a MLD and other disabilities, and my youngest who is fine just very full on. As you can imagine my life can be pretty stressful.
We live near MIL whose in her late 50s. No other family around she choose to go NC with DHs sibling and his other sibling lives hours away so very rarely visits.
Mil started hinting about moving in with us about two years ago, we ignored it at first and hoped she'd get the hint.
She didn't. A while ago I was talking to her about going on the council list as I need a adapted house as I'm slowly getting worse and loosing my mobility.
We rent so my landlord isn't happy to make the adaptations as this isn't our forever home.
She's now mentioning it more & more about how we need to apply for a four bed council house with en-suite for her (I know you don't get en suites with council!) and said she'll bring round her details to add her on. 

I've spoken to DH who has said he doesn't mind her moving in, and that it'd make sense so she's not struggling on her own.
I really do not want her to live with us, atm she's 5 minutes away and we see her every day and I find that to much, sometimes I just want to chill in my PJs with DC and switch off in the evenings!
Not to mention ill feel uncomfortable I don't like DTD with DH if we have visitors staying so we can kiss goodbye to what's left of our private life!
He won't tell mil that I'm not comfortable with it, I'm also worried because she's so young we could have another 30 odd years of this.
My eldest is unlikely to live independently so will be with us the majority of his adult life unless he chooses to move into supportive living so I also have to factor this in.
How do I tell mil she can't move in? DH says I'm being cruel. But the way I see it as my mobility and general life is declining I can't be looking after an extra person as well! It's really not fair.