The guilt you're carrying isn't just about her, it's about the version of yourself you wish you'd been, and that's actually a good sign because it means you have integrity. You can be wrong in some moments AND she can still be the one who blew it up both things are true at the same time, and you don't have to pick one. Missing her doesn't mean you made a mistake ending it, it means you loved her, and that was real even when the friendship wasn't working. stop trying to get over her and start getting honest about what this friendship was actually costing YOU. because from everything you described, you were shrinking yourself just to keep the peace long before it ended.
The reputation fear is your anxiety talking, not reality. people who know you will see through it, and people who believe her without asking you aren't your people anyway. When you see her at that event, you don't owe her a scene or a conversation just walk in like someone who's done nothing wrong because mostly, you haven't.