OK.

I feel like I've cut her an enormous amount of slack despite her doing any number of appalling things to DSD as well as putting DP and I through hell on the financial stuff.

I've been nice to her in the last 12 months, because, as I explained, I felt that would be better for DSD in the long run. It IS my nature to be nice or basically try to do the decent thing - ie forgive, forget, let's move on to the more important thing which is helping DSD a much as possible.

I have a problem with the way she has reacted because I really don't think it takes that much effort to send a short email response saying, "thanks for the info - that was really helpful."

I feel like I'm trying to do the decent thing and, as usual, she doesn't want to come to the party.

If she was a 100% nasty pasty, then obviously I wouldn't bother. But she does have good qualities and she does do some amount of self-reflection.

So ... having tried, what feels authentic to me is to tell her I'm over making an effort, that I find her rude and that I will no longer be courteous to her when she phones. I don't like being rude to people without explaining why and I simply can't keep the conversation short and business-like without feeling rude. Plus, I guess I want to write to her telling her I find her rude to get it out of my system. There seems no point me feeling she's rude without actually telling her. I don't expect THAT to achieve anything at all but at least I will have been honest about my feelings.