Why did the boston massacre ruin the relationship between the colonist and britain?

Because the British Soldiers killed/injured multiple Americans.  The American were already pretty mad at Britain, but this put the Americans over the edge. 

Urban growth invariably feeds increased commercialization and industrialization. it requires continually expanding land areas. when urbanization rates are high, and countries do not have the institutional and managerial capacities or economic wherewithal to manage such rapid growths, they exert intense pressure on the types and nature of the resulting settlements. they contribute to the development of overcrowded slums and shanty towns without adequate essential services and necessary infrastructure.-by asit k. biswas and cecilia tortajada