Daisy, if you can't attend a wedding without losing your temper, then it's time to end things. You must remember that this wedding isn't about you.
Truth be told, you can be angry at him all you like for not proposing and wasting nine years - but the fact remains that you allowed yourself to get into this situation. I suspect that most other girls would have ended things with him many years ago if marriage was important to them.
Forget the idea of saying "no" when he proposes. Why? A) it's unlikely he ever will propose and B) you'd just be wasting even more time waiting for it to happen. And forget the idea of having kids with this guy. If he can't get married after nine years, what makes you think he's ever going to have kids with you?
It's time to cut him loose. Based on what you've written, you clearly have zero respect for him so marriage at this point would be a terrible idea. You do have time to start again - but only if you can be ruthless and move on if a guy doesn't have the same goals as you.
Never regret anything that has happened in your life. It cannot be changed, forgotten or undone. So, take it as a lesson learned and move on.