My brother died last week, and I only found out -WWTPD?

Some back story: my brother was 13 years older than me and we were very close. 3.5 years ago, my DD told me he had abused her when she was a young child. I cut off contact with him then. 

About 18 months ago, my mum was diagnosed with terminal cancer, and I had to deal with my brother then (there were only the two of us, our other brother died twenty years ago.) I decided that I wanted to 'put aside' what he had done, so that we could care for our mum.  A few months later, he was diagnosed with motor neurone disease (ALS). He deteriorated quite quickly, but even though my mum died last December, I kept in close touch until July this year. To be truthful, I was really enjoying his company again, and I kind of figured that karma had already got him.

In July my SIL and niece came to see me about my mum's estate, and we ended with a huge argument and DH telling my SIL exactly what my brother had done to DD. It was awful. She asked for proof (!) and said that she didn't believe DD. She blamed her accusations on DD's poor mental health, not  considering that her mental health is a result of the abuse.

Anyway. This morning, my friend called me to say he was sorry to hear about the death of my brother. He had heard through another friend, and was surprised I hadn't told him myself. He couldn't believe that I didn't know. It seems that he died last week, and the funeral is tomorrow. I honestly thought my niece would have told me, as we have tried to maintain a relationship separate from all the other shit. I'm really devastated this morning that I had to find out this way.

Peas, I don't know what to do. Do I go to the funeral tomorrow or not? Do I contact my SIL or niece, or my nephew? What do I say? Despite what he did, he was still my brother, and there hasn't been a single day in the last three years that I haven't been in agony over this.