It is a long story so I have tried to summarise without leaving out anything key.
My father was abusive, has repeated affairs and new marriages with much much younger women. He treated my mother in unspeakable ways (which I have found out about since through asking, she hid it from us when we were children) and as such he someone I cut out my life and learnt to live without as a teenager. It was a struggle to get to this point and something I found very hard mentally.
My brother never really fully went through this stage. He knew what my dad did, agreed it was terrible and unforgivable but never fully stopped contact. He now sees him and denies any knowledge of the past, that my father did much wrong and just keeps repeating our dad loves us. It is literally like he has forgotten it. It almost plays mind games with me, making me think maybe I made it all up - which I know is not true!
Brother is now getting married and there has been a big disagreement over the wedding. He told me I needed to 'get over it' and put up with my dad at his wedding. I explained this is not something to get over. It is not an average divorce situation where you have to ignore and be civil. It was horrific domestic abuse which impacted my mother and us enormously. I said I needed him to respect how much pain it would cause us and how much it would take away from the celebratory day. I said ultimately it is his choice and I will do what I can to get on with it and be a supportive sister, but wanted him to think it through a bit more. To be honest, I don't know if I can do it and don't feel I (or my mother) should be put in this position. It is a pretty fancy wedding and I think future SIL's desire for 'happy families' has got in the mix of this too. She has never made much effort to get to know me and while I've tried suggesting coffees, family events etc she seems to want to keep distant. She is quite appearances focused and forceful - she definitely wears the trousers.
I ended up emailing him explaining my perspective, that I've moved on and don't want to drag up things from the past, because we have enough supportive family around us. We don't need someone who has caused so much pain back in our lives. I tried to keep it factual and about my perspective, rather than blaming him or saying I think he is in the wrong. I know that would just be met with hostility.
This was over a month ago and I've had zero contact since. DBro is a tricky character. He has ASD traits and isn't the best with social communication. However, I feel at a loss. This is not something to play around with. It is a really deeply traumatic topic and I feel dismissed. I feel like he doesn't believe me and it is starting to impact me a lot. The whole thing is really playing with my mind and digging up feelings I put to bed and worked through (with professional help) a long time ago.
Any words of wisdom?