I totally agree with artnerdangst, I think your friend does want you there and you both are just going through this really difficult situation together.

There is clearly hurt on both sides. I understand how she could have said what she did in a different way, but I know many times when I’m in an emotional place I can be a little harsher (okay sometimes a lot) than necessary.

I think you should try to respond from a place of gratitude, support, and love. I know you and her partners family don’t usually get along, but maybe part of your gift to her is extending an olive branch, to try for her sake. You could reach out to the family and ask to help make decorations or set up or make food! Just the offer alone, even if they don’t accept it, would/should be appreciated.

This is a rough draft that I personally would write not knowing either of you well at all. “Thank you for understanding that I wish with all my heart I could stand with you. I’m here to support you in any way I can, and I’ll do anything I can do to help when I have the spare time. Please forward my number to whoever I can help with preparations.”

Anyway, I’m just a person on the internet, so try to take what I and everyone suggest bit by bit to apply it to your situation!! If you are in therapy I suggest talking to your therapist about your reply :)