Well, you both made mistakes and learned from them, right? Similar mistakes, which ended up with possession and different things happening with them. You remembered yours while he didn't, because I guess you both were possessed differently? Or maybe you were just manipulated and he was fully possessed. I'm not sure.
Either way, I don't know what happened that ended up with you getting possessed or manipulated, but all that came after was against your will. I don't really know you, but you don't seem like a bad person. Not someone who would willingly allow themselves to get possessed and enslave a town. It's like how the other Tails can't blame himself for what happened while he was possessed.
I think... if you've learned from your mistake, as he seems to have learned from his, you shouldn't be blaming yourself. I wouldn't think little of what happened because of it... but it happened in the past. If you really feel like you've bettered yourself from it... there's no reason to blame yourself anymore. You've done all you can as a pony. Nobody's perfect. All we can do is strive to make ourselves the best we can be, and be there for each other.
[Private Visual]
Either way, I don't know what happened that ended up with you getting possessed or manipulated, but all that came after was against your will. I don't really know you, but you don't seem like a bad person. Not someone who would willingly allow themselves to get possessed and enslave a town. It's like how the other Tails can't blame himself for what happened while he was possessed.
I think... if you've learned from your mistake, as he seems to have learned from his, you shouldn't be blaming yourself. I wouldn't think little of what happened because of it... but it happened in the past. If you really feel like you've bettered yourself from it... there's no reason to blame yourself anymore. You've done all you can as a pony. Nobody's perfect. All we can do is strive to make ourselves the best we can be, and be there for each other.