My question is: What is the proper etiquette in dealing with a note like that? How to you response? Should you response?
Or do you just have a moment of silence for the lost friendship and move on; never to contact her again?
I guess I feel differently than most of the people who've responded so far. I think that long-term friendships can require give and take over the years, and that it's worth putting extra effort into confronting and solving problems in the rel
ationship, rather than walking away when a friend is rude or thoughtless. All of us can be short-term selfish and stupid, and a good friendship deserves a chance to confront those times and recover from it. I only walk away from a friend when something seems permanently unresolvable.
Your friend is definitely being rude to you. I'm guessing that she doesn't fully understand how your lives have changed with the baby, and she feels like she's been blown off, that you don't want to do things with her anymore because you're all focused on the baby now. She may feel rejected, and she's being a jerk about it.
In your situation, I might respond to her note "We're not making excuses, we just can't go. Why are you being nasty about it?" Then I'd have a conversation with her to really explain how your lives have changed, and that you still care about her and want to see her, but it's much more difficult to do some activities now. Offer some activity on your terms (e.g. come over for coffee while the baby naps), when you turn her down for something she invites you to.
(I have a new baby at home too, and I think that people without children may simply have no idea how much time and attention they take, and how much more difficult social activities may be for you for a while.)
If she continues to be rude to you about it, then you can always respond "Look, we've talked about this, we can't do X right now, and if you really want to see us, you need to Y." Confront her when she's being rude, while still giving the friendship a chance.
If she just refuses to understand or change, then you can drop the friendship without remorse.
Just my opinion. I sympathize, and I hope things work out with your friend!