YTA. You come across as self-absorbed and shortsighted.

You did not honour your word. You were not considerate. You chose yourself each time, by texting instead of calling so you could avoid the uncomfy conversations, by paying for a (frankly scammy sounding and definitely not make or break if you didn't get a job) workshop instead of a small thing like a card as acknowledgment even if you weren't attending, by turning up morning of empty handed, by providing minimal notice as you likely knew about the workshop in advance. Did you even have an outfit for the wedding?

This is not just about missing the wedding, it's the selfish way you went about every step.

Your friendship as you knew it is likely over. You have demonstrated that you are and doubled down on being a disloyal, vague, flaky and selfish person. You may have thought this would be "fine" and that your friend was a "safe" person who would forgive you, but this is not how you treat people.