Sort of confronted my abuser (dad) as a child (age 15) when I disclosed to my teacher what had been happening. He had assaulted me daily from age 11 to 13 then stopped when my mum found out. Her reaction was to tell me never to talk about it again and that I'd made her very angry 
The reason I disclosed when I did was because he had started grooming my younger sister. When I told my mum this she said "Don't be silly darling, he doesn't even like her." 
Anyway I had the full script from him:
It didn't happen at all
He was just playing a game and I was mistaken
It was all Esther Rantzen's fault because this stupid Childline stuff put ideas in kids' heads
I must have made it up to punish him because I'd asked for a new computer for Xmas and he'd said no
OK, it did happen but I wanted it so it was my fault
I was very flirtatious so he couldn't help himself
I obviously liked it because otherwise I would have killed myself or run away
I must have liked it because I continued to spend time with him
It was all my mum's fault for being frigid, because A Man Has Needs
More and more stuff which I've forgotten, all equally wounding and scarring to hear as a child.
Unfortunately there was nobody in the house to advocate for me, nobody was on my side. I was the troublemaker. I was the one causing problems and "washing my dirty laundry in public". My mum told me "You can drag yourself through the dirt if you must but you're not bringing this family down with you." 
The police declined to prosecute, btw. It was the 80s. They didn't even bother interviewing my sister.
What I'm saying is, be prepared not just for his denials and blame-casting onto you, but also be prepared for the rest of your family to turn on you. If you do go ahead with this, it can be very freeing just to look the bastard in the eye and say "I know what you did and you will burn in hell", but make sure you have strong support around you.
If this has come to your mind because it's Xmas and you're expected to spend time with the abuser, can you think about making an excuse to get out of it? Sudden bout of stomach flu, etc. Terrible bug been going round at work, spent Xmas day on the toilet, blah blah blah.