Summers acted under the influence of the Phoenix Force, kid. That makes people act how they normally wouldn't. It's not your fault. You're just a kid. Messiah or not, you're just a teenager. And you've never really gotten the chance to be a kid before.
In this life...you can't really blame yourself for things that were out of your control. The Phoenix Force is one of those things that we can't really control, not matter how much might want to.
For what it's worth, a lot of blame lands on the Avengers' too, for what happened. I'm sorry.