You have NO personal experience as a carer and are so VERY clearly not educated in the area!
Myself and others who HAVE done it for many years and have both the experience AND professional knowledge of what's involved have REPEATEDLY pointed out that there are very many reasons why professional care is preferable to inadequate care provided by even the most well intentioned of people who don't have the training, experience or knowledge to provide care.
We have SEEN the results of such situations.
"I don't get why someone who loves his parents so much will be so thoughtless when it comes to this one thing - denial?" I really DON'T THINK dh is the one in denial! You are being incredibly arrogant, thoughtless and selfish towards HIM actually. Maybe he is being honest about the limitations of his abilities and knows that his parents won't want him doing very personal, intimate care! I've known VERY few mothers that have felt comfortable with a SON doing such things as incontinence clean up and bathing, and very few sons comfortable with it! How many sons want to be inspecting under their mums boobs regularly and checking for and treating fungal infections? (Fairly common as we age). I'm wondering if you were hoping for more support from this thread to show your dh how unreasonable he was being and now you're pissed as that's not happened!
Does he even WANT to be a sahd?
"Yes, it may mean giving up whatever you would normally do for those two hours I realise that..." You are SO unrealistic! 2 hours MINIMUM, there's also travel time to and from, waiting for the delivery to arrive (I use Sainsburys who have a 1 hour delivery slot but many have 2 hour slots so you could well have almost 2 hours JUST waiting for the delivery to arrive! THEN there's the unpacking, dealing with any unsuitable substitutes, possibly dealing with a confused relative who keeps taking stuff out the fridge while you're trying to put shopping away, or who argues they didn't order X etc you're COMPLETELY unrealistic. I'm housebound and get my groceries delivered and I'm currently still compos mentis, it takes about 2 hours before the delivery slot starts for me to prepare then I'm sat waiting up to an hour for it to arrive, then it takes about 20 mins to move from doorstep to kitchen (without actually unpacking anything yet) and deal with any unsuitable subs or complaints/breakages, a good 90-120 mins to put away "properly" - that's about 6 hours! And I'm no way as frail or needing support as you're talking about! You're clueless!!
"but most people would have teenagers so no need to help with homework or do a bedtime routine."
More stunning arrogance and ignorance from you! teenagers need just as much support as younger children, just DIFFERENT support, they're dealing with the physical and mental changes with adolescence, bullying, friendship issues, peer pressure, first relationships, school pressure, exams, pressure relating to extra curricular activities... They need as much parenting time wise as younger children!
"I'm entitled to have an opinion about raising my own children and to express that opinion." And those of us with the ACTUAL EXPERIENCE of having done so/are doing it now are entitled to tell you that you don't know what the fuck you're talking about!
"I'm a management consultant but not sure why that would be relevant (hence why I haven't mentioned)." Oh come off it! Of course it is relevant that you have a job that has NO connection whatsoever to caring!
"Actually I have bipolar disorder and have been in a psychiatric hospital twice so that's a bit of an unfounded assumption" then you should have a better understanding and appreciation of why people want to protect and maintain their mental health by not taking on a role that would cause them too much stress!
"Carers won't do that stuff." AGAIN advertising your ignorance! It can be difficult to access and isn't as available as it should be, but yes, community carers DO do things like shopping and running other errands, eg posting mail etc they also visit as much for the social/mental health needs of their clients as practical needs, gardening services are provided by councils for those unable to care for their gardens themselves, cleaning services too - you so VERY CLEARLY have ABSOLUTELY NO IDEA of what people's needs are and how the various services work, completely and utterly clueless.
37?! Wow! You really are old enough to know better! It's embarrassing how ignorant you are at your age actually.
In addition even if you have your first child next year that means IF Your mum stays relatively well until she is say 70, as she is 56 now that's in 14 years, your eldest will only be 13 and still very much needing parenting, you'll be 50 and likely starting to feel your age, possibly with a disability or more health issues of your own. I'm 47, have major mh issues and a physical disability, I'm knackered most of the time and actually my friends of a similar age WITHOUT Health issues tell me they're also knackered and struggling to cover just looking after their immediate family.
What if your bipolar flares again badly? What if you have a child with health issues (more likely as you're an older mum but can happen to anyone, my dd is 18 I was 28 when I had her she also has a disability that has resulted in many hospital stays and care required)? What if dh becomes sick or disabled?