Bit of a crap title, sorry 
After years of shitty behaviour from my father, an argument 2 years ago put an end to our relationship (as far as I'm concerned, at least). He's not prepared to discuss it with me and believes he did nothing wrong and I can't continue pretending his behaviour is normal so we haven't seen or spoken to each other since then. I'm offering the same level of effort as he is...apart from this one issue.
He continues to send a birthday and Christmas card. I don't want either and believe he's only sending them to keep his conscience clear.
This in itself isn't a big issue but he passes the cards to my dsis to pass on to me. It upsets me because I feel like both dsis think I'm being the unreasonable one by not making any effort with him and are also not prepared to talk about the situation with me. One dsis was more upset over the incident 2 years ago but is happy to forget about it rather than tell dad he upset her.
Each time a card comes via dsis I feel like I'm back to square one of doubting myself. I remind myself that he did do the wrong thing and I was right to stand up for myself and that dsis is just stuck in a lifelong habit of doing what she's been told to by him so maybe I shouldn't ask her to stop delivering the cards. Life moves on, I forget about it all and then the next birthday or Christmas comes around again!! I'm sure it will be less of an issue as the years roll on but for now, I'm looking for advice whether to ask her to stop bringing the cards, ask him to stop sending the cards (altogether or via dsis) or just suck it up and learn to not be bothered by any of it 