AIBU to refuse care for my late dad’s wife?

OMG you knew her stayed at her and your dad's house from being 6yo & you don't feel anything for her?

YAB extremely U imo. I don't care about blood relatives, it's irrelevant, she's a human that looked after you fgs. Pull your fingers out and help support your sibling.

She's not your mum, you aren't close to her daughter, it doesn't matter how your dad felt because she obviously didn't build a caring stepparent relationship with you and your siblings.

She's not your problem. Your relationship with her ended with the death of your father. Your half sister can bugger off with the emotional blackmail and bad-mouthing.

In all honesty I wouldn’t care for my own mum and I like her, if it’s something like a one off picking something up from the shops for her I’d do it, but otherwise just tell her you have other commitments so you couldn’t do it even if you wanted to (even though you don’t)

OP did provide care for her own mum though. It doesn't matter if she did it herself or paid for care.

Not in a month of Sundays my lovely….hard no….and I’m normally a bit of a softie x

I can't believe anyone thinks you should care for her if you don't want to. You don't owe anything to the person who broke up your parent's marriage.

Totally not your responsibility, apart from your connection to this woman through your dad she is virtually a stranger who happened, rightly or wrongly, to remove your dad from your own family home.
Let HER daughter care for her and ignore any comments she may be making about you, totally irrelevant.
Nobody gets care as a right, it is a privilege that has to be earned. You reap what you sow in this world. If you felt she had earned and deserved your care you'd be giving it. She didn't and you're not. End of.

Surely it was the OPs father who " broke up the home". It was him that was married with young kids. Why does she get the blame?

Nothing unreasonable or unusual to not want to do care. My dd made it quite clear she wouldn’t be doing any care and is sticking to it. I rarely even get a cup of tea in my house, and don’t go to hers,but that’s her nature. I pay for my care which of course is eating away at any inheritance and there’s likely to be evening care soon. But the care is carried out by people who want to do it and are friendly too. YANBU

So when you had the 40% of your time with your dad she never ever looked after you or did anything to care for you?

It sounds a bit sad you're not close to half sister or your Step mum having spent 40% of your time with them from age 6. It's hard to imagine what the dynamic was. But that's a separate issue, no one can make you be a carer.

How much time have you spent with her since your dad died? Did the relationship stop at that point?

Give over, the OP has her own feelings on her own experiences growing up as she is well entitled to do.

I was in neighbours and relatives houses regularly that doesn’t mean I owe these people a debt of care nor do they me of anything should happen to me.

Care of our own children is an absolute responsibility, care of parents has limitations and is based on circumstances, care of others is a complete choice not something that a person is obligated to do.

I’m a volunteer who works with the elderly in the community and I choose to use my time that way (I don’t chastise people on the internet for not using their free time the same way) how others choose to use their time is entirely their own personal choice

To not do anything on the basis she is not blood related is heartless. If you like her and have any compassion you would help out. Which is it?

No way would I be doing amy care whatsoever for this woman.

Absolutely hell to the no, YANBU

'Care' from the family needs to be given from the heart and if you ain't feeling it, then it's not going to be good, and for what's it's worth I would likely feel the same in your shoes. Your step sibling probably just doesn't want the 'burden' all on her shoulders so she's trying to guilt trip you.
It's HER mum, not yours, so don't fall for it - it doesn't matter HOW GOOD of a step-mum she was, this is not your responsibility.

ETA: I have step children, I didn't break up their parents marriage, I 100% do not expect them to look after me in my later years! The mere idea is preposterous!

We have all had messages to say our dad would be disappointed and saddened.

I would be pointing out to everyone your step-sister has said this to that you, your siblings and your mother were 'disappointed and saddened' when your father had an affair with her mum and left you when you were very small. The guilt trip is well out of order.

She "raised" you? No, she broke up your home, didn't she, from what you say? If that's the case, I'd do nothing for her. Your half-sibling is innocent, and I've got some sympathy for them, but your stepmother was an adult and made her choices. Who would want to do anything for someone like that?

I would expect it from a stepson!

While it’s totally up to you to refuse to help, you did say that you spent 40% of your childhood with her. And although not ‘warm’ did she e.g. feed you, wash your clothes, clear up after you, make sure you went to school, helped with your homework etc? If so, I would probably offer to help in some way.

You don't have to look after your own parents so why should you look after some woman who dossed with your dad ad broke up the family? You reap what you sow,

I’m sure the op would have preferred to live with her mum and dad 100% of the time. This woman was not a motherly figure to her, read her posts.
Nobody would expect shit if you were stepson, OP. Dont feel a single ounce of guilt.