Your father and you have been the victim of abusive behavior. There are laws on the books (incidentally, I am sorry about your father passing away). Some of those laws prohibit what's called "elder abuse," and there are adult protective services in many communities that take a special interest in this sort of case.

Even if the abuse upon your father occurred some time ago mainly, the statute of limitations will run from the time when an offense is discovered, rather than from the dates when the crime actually occurred.

You have just recently discovered what really was going on in your father's life, how he was being mistreated and abused while he was elderly and disabled.

This has to be brought to the attention of the authorities. You could start with a police report, and see what they have to say about which agencies might handle something like this in your town.

As for the real estate itself, it would have been your father's home as his separate property, having passed directly to him upon your mother's death as a joint tenant by the entirety with your mother.

However, widows, even if not on the deed, are protected by law, so that they have a right to a share of their husband's estate. Therefore, the evil second wife does have some rights in the estate. Often the court will award her the entire house.

This is where you certainly can come before the probate court and explain what was going on, what with her seeing another person, being defensive and obviously trying to keep people from knowing what she was up to, and being abusive toward your father.

By rights, the court should fine her, put her in jail, or at lease prohibit her from profiting from her wrongdoing by way of inheritance.

Other answer does not take into account that you're in England right? Here in the U.S you would be able to contest anything and his estate would be handled in probate court, that's here, the laws are different in the UK, so please consult with a UK lawyer to see what your rights are. GOOD LUCK!