Would this level of caring for a parent be too much?

I’ve been through the elderly parents stage, and in your case your parent is being totally unreasonable- you can’t give your children a childhood, keep a roof over their heads, have a reasonable level of mental/physical health yourself and provide that level of care. And assuming this is something that isn’t terminal, this could last a very long time ( my mum needed carers for 15 years). You can’t imagine absolutely say no to this level of care and just be a normal loving daughter who pops in to see them, takes them a meal round once a week- but also ensure that they are getting the professional care they are entitled to, and which will give them a lot better chance of staying at home than wearing their daughters out.

My DM has a cancer diagnosis my DF has depression. She is currently in treatment - daily. It will last 6 weeks. She will near after this scans, a couple more operations.
DF isn’t looking after himself well at all.
I am happy to help regular in the short term but long term if their level of need continues I will burn myself out. Also I have to travel to help them. So that disrupts life at home.
Sadly at some point - I hope with support. They will have to choose a cleaner and maybe some caring help. I cannot do it all with the help of siblings. It isn’t sustainable long term.
Neither is it so for you. Good luck with boundaries. I’m starting to construct mine

Even if you didn’t have children this would be too much!
Walk away. No half decent parent would ask this of their child.

For a short term illness only - I'd do it. My dad has terminal cancer, and I've already accepted that I'll likely need to provide care at a high level for a time before hospice care or chc can be started. But for years? Absolutely fuck no. Not a chance. This is so unfair on you - and your siblings. How can a parent do that to their own children? It's beyond me.

No, you're going to kill yourself, but before that happens your relationship with your kids will hit rock bottom, they'll go off the rails and be left with awful memories of you and their grandparent and lifelong emotional difficulties.

You and your sib need to discuss to agree a proper action plan to force them to accept paid carers coming in. You will need to be tough. But it is essential to protect your own mental health. good luck.

They can only refuse carers because they know you will do it.

Also, you can't do this without sacrificing your children's childhood.

There are elements of that that you and your sibling could do - the housework/cooking potentially and the taking to appointments - but otherwise it should be exclusively done by a Carer. It is not remotely fair to expect you to help with toileting in particular, and time wise with a young family you will grind yourself into the ground if you don’t get practical support with this.

Ring Adult Social Services and ask for a needs assessment.

Let them deal with this situation.

Absolutely not. They need to accept that they need external help.

Crying and guilt tripping from parent or your sibling?

Well no as this parent needs proper care.