Remove any mussels that are broken or which do not close immediately if tapped. Scrub the mussels well with a wire sponge or brush.
Bring a large pot of salted water to boil for the pasta and tomatoes.
Blanche the tomatoes in the boiling water (one minute) . Remove with slotted spoon. Place in a bowl of cold water to stop from cooking. Peel, the remove seeds and cut into bite-sized pieces. Set aside.
In a large skillet, add a few tablespoons of olive oil and sauté the garlic until golden. Add the mussels and then the wine, and cover. Cook for about 5 minutes or until the shells open (discarding any mussels with a shell that does not open). Remove the mussels from the skillet with a slotted spoon and then remove all but 12 mussels from their shells. Place all shelled mussels back into the skillet with the remaining liquid.
In a separate skillet, sauté the tomatoes in olive oil. Add salt and pepper to taste. Simmer over medium heat for about 10 minutes. Add this mixture to the large skillet containing the mussels and heat together. Add back the mussels remaining in their shells.
Meanwhile, cook the spaghetti until al dente (two minutes less than package recommends). Drain the pasta and add it to the skillet with the mussels. Mix together over medium heat for about a minute.
Serve immediately, evenly distributing the mussels.