Her death did greatly sadden him, as evidenced by the quote you've included, and people's personalities are created from their experiences, so, indeed it's possible. But remember though, Bolsheviks, and other Russian revolutionaries, as a whole were not nice people. Bolsheviks were involved in Terrorism in Russia and abroad for years. The very foundation of Leninism is a small central party ruthlessly securing the revolution. Leon Trotsky is known for his massacre of the sailors at Krondstadt, rebels who were merely socialists demanding justice and democracy in the Soviet Union. Stalin's ruthlessness wasn't at all unaccountable within the politics of the time. Stalin's regime would rely on the "ruthlessness" of thousands of other officials to function. Stalin's reputation is still well deserved, he was constantly paranoid, held innumerable grudges, taunted those sentenced to death in execution orders, was heartless towards his son, just not unaccountable.

After the death of his first wife, during his imprisonment in 1908, he may have begun to hold more grudges against perceived slights, a classic trait he would be known for, but it's hard to compare his life after the death of his wife to that before. There's not too much to base his personality on prior to 1907, all we can say is that he had many romances, was respected as a member of the RSDLP and as a pundit, engaged in some bank robberies, and was a good labor organizer in Baku, Batum, and elsewhere. He had a doting mother, he had a love for adventure, but I don't know of any source that can give an answer answer as to whether he was more ruthless either after his wife's death or because of it.

Source: Steven Kotkin, Stalin Paradoxes of Power Vol I