Edward brings Bella to play baseball with his family, but in order to get to the clearing where the family will play, Edward must run there with Bella on his back. Bella had a bad experience feeling motion sick from the last time, so she refuses. He "talks" her into it by kissing her, which is a dangerous thing, as he is a vampire and part of him wants to kill her. She reacts strongly, by grabbing him and kissing him back forcefully. He stops the kiss because it was too intense. Instead of her standing still and letting him kiss her within his control, the kiss became very passionate and dangerous. If Edward loses his control at any time, Bella could die. So he curses and remarks, "Bella, you'll be death of me" because her reaction was so strong. He is afraid that he will lose control and hurt her.
Bella and Edward are going to a field to play "Vampire Baseball," not soccer. He is going to run through the forest because they can't drive. He is intending to carry Bella on his back. Before they leave for the clearing, Edward kisses her. He has told her in the past not to move, but she can't help herself and grabs him around the neck. As they kiss each of them becomes more aroused. Edward tells Bella that she is going to be the death of him because he wants her so much he feels like he is going to die unless he takes her. She replies,
"You're indestructible," I mumbled, trying to catch my breath.
"I might have believed that before I met you. Now let's get out of here before I do something really stupid," he growled."
He knows that if he loses control he will begin to drink her blood and might not stop until she is dead. The stress is strong for hinm and the quote he uses is a figure of speech to indicate to Bella how difficult she makes things for him when she gets so passionate.
she was afarid to ride on his back to the clearing because of the last time so he kissed her and she kissed him back. he is afarid in the books that he will lose control and kill her. and if he killed her it would kill him. or he would kill himself.
It is because Bella kisses him in a way that was too much for him to handle. He cannot handle Bella since she pulls him in and she is too much for him so he tries to control himself around her. However, when she kisses him, it was too much for him and he almost lost control.
Edward eludes to the fact that Bella is very appetizing and he may go crazy from being around her scent so much. Edward once said something along the line that being close with Bella is like being an alcoholic that's been invited to a wine banquet but can not enjoy the tasty wine but be plagued with the scent of it. In that scene Edward was really close to her and she wasn't being too cooperative in staying still so he could control himself. So he said that to her to let Bella know that doing things like that makes him loose control and him loosing control is going to be dangerous for the both of them.
if you are actually so obsessed that you have to go on a stupid website and ask people, you deserve to not know
When he says this, Bella is kissing him greedily. Edward fears that if he and Bella get too intimate, he will lose control and kill her. That's what he means when he tells her that she will be the death of him. If he killed Bella, he would die himself. It was a joke, on Edward's part.