It wasn't because of Jasper. Jasper was just the catalyst.
Basically, and if you've read the twelve chapters of Midnight Sun you'll get what I'm talking about a little more, Edward is petrified of the idea of Bella getting sick or being injured. But what horrifys him the most, is the thought of Bella getting changed. It's not because he doesn't want her to be like him, he actually wants that more than anything EXCEPT Bella's happiness. And he is 100% positive that if he ever changes her, she'll despise and hate him for the rest of her existence for ending her life because he wanted it. And he can't deal with that. He doesn't know how his life would continue if she hated him.
So, when Jasper attacks Bella, it all comes crashing down on him, he's always known how breakable she is, how easily destroyed, but right then it was put in perspective for him. He saw just how easily it could happen, just because of one paper cut! So, his only solution is to take himself out of the equation, take his dangerous influence out of her life. To keep her safe. So there's a less likely chance biting her would be necessary, so she won't resent him later. He can live with her marrying someone else, having a life outside his own, but he can't live her hating him. It would destroy him.
So, he leaves. He's fully aware of the pain this will cause him, but he does it for her. He doesn't know how badly it would turn out for Bella, but he knows what it will cost him. And just in that one act, show a tremendous amount of love and care for Bella. We see a glimpse of just how much he cares for her, although we don't find this out until the end.
Plus, it turns out to be a good thing in the end anyways. Edward sees the depth of the feelings Bella has for him and Bella learns how much he cares for her and how she cannot live without him. It turns out to be a very enlightening experience for both of them.
Now back to the question: Do I Agree?
I don't know. It was a very complex set of events. That all tied together in the end. I cannot agree or disagree with his actions, I cannot judge him on what he felt as right. In his mind, this was the right thing to do. And in a way it was. But in another way, it was not.
There is no answer to this question you have presented me with.