Dizzy - thank you for responding to my point. To be honest, it did sound harsh when you made that response to yellowraincoat.
However, my thoughts on your question. I have typed this several times, and it sounds really pompous and smug. I'm sorry about that. But here we go:
I think it is important to consider how the things I do affect other people - especially the people I care about. If something I am going to do would cause someone I care about to be hurt then it wouldn't give me any joy, and I wouldn't do it. Or I would try to find a way to do it that causes least pain. At the very least I would be sensitive to the fact that it might hurt them, and would make allowances for that.
So yes, as it happened I did invite people to my wedding who I didn't know, and in a couple of cases didn't like. But the offence my not inviting them would have caused would be greater than the negative affect they would have on the wedding.
In your case, you say that you wouldn't have enjoyed your wedding had your mum been there. I have assumed it was a fairly short registry office do - forgive me if my assumption is wrong. I really don't see how the lack of enjoyment you would have suffered by her being present sitting in a chair watching was a worse thing than what has actually happened, with your party spoiled and all of you apparently upset for several days afterwards?
So maybe I take the path of least resistance, maybe I am a "people pleaser" - I don't know. But I do think that the way I live my life and the chioices I make don't just affect me, they affect everyone around me. And I bear that in mind when I make choices.
However, hindsight is a wonderful thing. What is done is done. It might help you though to think about how you would feel if your daughter said to you "I didn't invite you to the most special day of my life, Mum, because I didn't want you there. I wouldn't enjoy it if you were there." I know you haven't said this to her is those words, but you have said it here and it isn't too much of a reach to think that she might be feeling this is why you didn't invite her. And that must be devastating.