The woman he married, while beautiful, had a black heart, and when Snow White began to grow up, and her beauty began to show, the Queen became jealous.

The evil Queen commisioned her hunter to take Snow White into the forest and cut out her heart, to bring back as proof of the deed. (actually, i have a version where it's her liver, and the queen ate it. Ew.)

The hunter couldn't bring himself to kill the innocent little girl, so he let her go in the forest, with the warning that if she ever returned to the castle he would be forced to kill her.

The little girl ran into the forest, wandering, lost, until she came upon a small cottage in a clearing. She entered the cottage, and explored to find that there were seven of everything, and everything was smaller than normal. Tired, she went to sleep in one of the seven beds.

Upon returning to their home from a long day of digging at the mines, the seven dwarfs who live in the cabin find Snow White asleep in the bed.

Next morning, the dwarfs hear Snow Whites story, and agree to let her stay with them, in exchange for her cleaning their house and cooking meals.

Years later, the Queen finds out that Snow White is still alive, and attempts, three times, to kill her. The Dwarfs thwart her plans each time but the last, whereupon the queen gets her with a poisoned apple.

Snow White lies in a glass coffin until a Prince rides through the forest one day, and wakes her with a kiss. They journey back to his castle and are married to live happily ever after.

In all the versions i've seen, the Evil Queen does, but the death varies. In one version, she cracked her magic mirror on finding that Snow White survived the apple, and slowly fell apart at the wedding. In another, she dies escaping the dwarfs after giving the apple to Snow White.