What should I do?

This is a very sad story but there is nothing you can do but learn to accept that your brother has never been the person you thought he was, the person you wanted him to be and in your parents old age he proved to you just what a useless brother and son he was You have spent all your life adoring someone who wasn’t real, they were a figment of your imagination they were only in your head what you wanted them to be and you had a big wake up when your parents became old and ill
You did everything you could for your mum and dad and should be proud of how well you looked after them at the end
I m afraid the only peace you will find is to accept that your brother is not the nice person you wanted him to be
Concentrate on you and your own family you can’t change the past

I agree with Bluebell this situation is out of your control and you can’t change how you want your brother to be. Try to accept him as he is now was he ever as nice as you really thought him to be. Family is never going to be what you want them to be that’s the same world wide be happy with what you have not with what you want to have

I agree that there is little to do. I don't recommend counselling in the immediate aftermath of grief, but after a year (and a strange year at that) you may find it helpful. You may be able to find a place where you can hold both the love you had for your family and that you cannot do anything about your brother's behaviour.
I note the age difference and wonder if you adored him almost 'from afar' without being aware of his nature.

I often note that as parents get older, it is the slightly disappointing child who steps up to help, whilst the 'golden child' continues with their privileged place in the family and does nothing.

I grew up in a very close family who meant EVERYTHING to me

Statements like that always frighten me. It is because one knows immediately that whoever made that statement has so based their whole life on being what they are determined it should be that they have willing distorted reality to make it conform to their delusions.

Your brother is a selfish and unkind man, who, if I read between the lines correctly, cloaks his unpleasantness by claiming to be religious, I suspect a religion with lots of rules that promise hellfire and damnation if you break them. You 'love' him because of your belief that family is everything means that you ignore everything he is and the way he treats you. Such a man is not loveable in any real sense.

I loved and cared for dad for the last three years of his life, so sadly during this time my brother, nice and nephew barely saw dad and this hurt my dad so much. What was there to stop your brother and his family visiting? I am sure you would have welcomed them and if they really cared they should have been prepared to face opposition to visit their father.

Your brother is a selfish man, ready to let you do all the work looking after your parents in what sounds like difficult circumstances. When your father saw the light and realised his daughter was worth 10 times his son, he changed your will and when your brother discovered that he and his family would not get the money they had expected, they all walked away. They do not love you, never have and were only there for the money.

I feel so sorry for you, I think you should seek help from a councillor to talk through the delusion you have so devotedly built your life around and to help you build more realistic hopeful ambitions for your life and your family. A councillor will help you come to terms with what your brother is and that any relationship with him has now ended.

Whilst I don't disagree with PP, your final sentence tells me you're not ready to accept that your relationship with your brother is dead. I'd advise reaching out to him one last time so that you know in your heart you've done everything possible to repair the breach. Accepting that this is the final effort on your part is important, though.

I'd make no reference to what's gone on in the past except to say that you're missing him in your life.

Wishing you luck, whatever you decide to do.

This situation is entirely of your brother's making. I think you love the brother you thought you had, not the real person. It's another bereavement for you, sadly.

Please don't waste your time and emotional energy on a relationship that's never been there for you. Focus on your own family, and remember your parents and the happy times you had with them.

Unfortunately, those that are put on a pedestal usually fall off with a big bang!
Your brother, sad to say, despite his religious beliefs that may preach humility and caring for others, has decided he is too good for mere mortals to be associated with himself.
Sorry if I sound harsh, but I have seen this happen several times in friends families. No contact from one member until money is mentioned!
Your father, quite rightly IMO changed his will. If his son and family couldn't be bothered to visit while he was alive, they were not going to care when he was dead. You bore the brunt of the care and upheaval to your home, willingly and even though you did not ask for a reward or expect it, your father loved and cared for you enough.
Sadly, you will have to let your brother go his own way. If you continue to try to contact him, or expect a response from him, you will be even more hurt and disappointed than you are now.
Just remember your dad for the man he was. At least you have those memories to comfort you - your brother doesn't and possibly feels guilty because of it, hence the lack of contact.

It was obviously your father's right to do what he liked when making his Will but he has caused unhappiness to you. When people leave money unequally, this can happen. Is it always wise?

I am very sorry for you and hope that, one day, your brother will talk to you again if this will make you happy.

If it were me (the other comments notwithstanding), I would want to reach out to him just to say "missing you".

If you do this, don't refer back at all, just hold the door open so he can step inside if he can.
...Then, try to put all this aside. He is the person you know, not the person you imagined him to be.

Good luck. You are clearly stronger than you think.