I commend your efforts and understand what you're trying to do, but you should have learned by now that speaking out and trying to defend her is pointless, as well as harmful. The fact that you've taken this amount of time and energy on her, once again, proves it's still stressful to you. Let it be,

And to be quite honest, if people refuse and don't want to see Alpha in a new light, then don't fight them on it. Alpha doesn't deserve to be redeemed, in my humble opinion. Maybe to you, but that's a different case and I'm assuming you two may plan on getting back together someday, so there's that. For some of us, we won't change our minds until we actually see her do things. That's how it is.

Ignore places like these communities. Yes, threads like these still happen. That is nothing new and Alpha isn't special in that sense; everyone gets the same treatment. Yes, it's sad, but so is the entire point of the community. So stop going to them. I'm honestly surprised you even showed up at all. You need to let go already.