You clearly have declined and feel rubbish about the late invite so YANBU, your feelings are valid.
Times I have accepted a late invite:
- Friend texts and says hi I’m a bit bored today do you fancy going to the pictures? I was free and fancied it so I went.
- Friend’s very small wedding, it was family only so no invite, last minute a family member pulled out, I suppose I was “on the reserve list” and got invited. I understood about their limited budget and went along.
- i asked friend if she wanted to meet up over half term, she replied that she was sorry but she was busy then 24 hours later text back saying actually how about tomorrow afternoon…I accepted as it sounded like she had thought about it and moved things around to make space for me.
times I have not accepted
- happened to be in the middle of a conversation with a “friend group” realised that they had all made a plan for a meal out the next day…embarrassed they said “ Rainbow are you coming too?”
- Not invited to the wedding but invited to the hen do, spent time and effort at the hen do making arrangements, giving lifts etc. no problem, assumed the wedding was small-budget etc. Discovered at the hen do that it was a large, church hall, buffet type party with no real restriction on numbers. When the bride realised that I knew this she tried to style it out by saying “oh yes of course you’re welcome to come”
so yes it depends on context and your feelings about the invite and the person really.
one last one, I was invited somewhere as a new mum by accident. She sent the text to me instead of somebody else by accident. I replied “ha ha this one’s not for me Sheila” and she then said (again in embarrassment) oh but you should come it would be great to see you!!
I was bored on Mat leave so I went along, I had a blast and we’re still friends almost 15 years later.