I'm currently reading "Mrs Lincoln" (Janis Cooke Newman).

It's a fascinating historical fiction about the wife/widow of US President Abraham Lincoln. She was strong, smart, a bit mad, and obsessive. She was committed (by more than a dozen legal witnesses and her own son) to an insane asylum about a decade after her husband's assassination. Her story is told in first-person narrative.

I'm only in the first quarter of the book (a proof copy I got a hold of) but am completely absorbed.

It was released in the US a couple of years ago as "Mary".