Struggles with conventions for work/academic emails - advice?

I really struggle with email etiquette generally, even more than I do in-person conversations. As hard as it is to judge what people are thinking when I'm talking to them in the moment through facial expressions, it's even more difficult for me when I just have a screen and some words to try to analyse. I often panic when sending emails, and I'm really reluctant to check my inbox because of it - which makes things difficult, because, as a university student, a lot of information we get comes to us via email! For example, there's one situation at the moment that's causing me a lot of unnecessary stress, that I feel like I should know how to deal with, but absolutely don't; because I just don't get the social conventions for emails!

A group of us at my university were invited to an event a few of our professors are running - whilst academia-focused, it’s pretty casual, so there’s no formal RSVP (although there was a line about letting the professor who sent it know if we'd like to come along.) I’m already busy that day, but I appreciate being invited and want to be kept up to speed on more events of this type that I might be able to actually attend in the future.

I’ve been overthinking whether I should respond and thank the professor for the invitation and explain that I can’t go, or if I should ignore it and not respond. Ignoring it feels rude after it was sent to a group of us with particular research interests, as opposed to everyone on course, but I’m also hesitant to reply because I don’t want to clutter up their inbox just to say I can’t go.

Is it accepted/polite to respond to invitations like this, or is it more typical to leave it? If anyone can offer any advice on this specific situation, or how to navigate work/academic emails more generally, that would be really appreciated!