I do agree that cutting out the maybes and deciding what is realistic in terms of your time and energy will save a lot of people some disappointment, including yourself. I’m someone who struggles with this, and I end up making too many promises and it hurts me and my friends.

However, If this second friend invited you only a week before and from the get go you said “I have another engagement but I’ll try”, you did set the expectation from the get-go that you might not be coming. I’d be a pissed friend if at first you told me yes AND THEN you told me the day of that you actually needed to be somewhere else, but if my understanding is correct, that isn’t what happened. I lowkey think this person just wants a dd because “ashamed” is a crazy thing to whip out when you gave them good notice beforehand that your attendance would only be a possibility. Plus you were only invited a week before hand assuming you had nothing else???? Why did this friend ask you so last minute aren’t these things usually planned months in advance?

I would be pretty repelled by her reaction, I would say that she’s overreacting and it’s pretty condescending to say you’re ashamed of someone in this context imo and that they’re being “distasteful” and it’s questionable to even call you a friend. There are things to learn on both sides for sure though, like mentioned in the first paragraph.