Sudanese executive committee member Owak Awak said the small community of about 1000 people was in absolute disbelief about Kuol Piom's death.
Mr Awak said it was struggling even more to accept his cousin Mr Piom killed the woman he loved, Sammi Hewitt.
"No one thought he could do that," he said.
"He was a very outgoing person, very social person, who was kind and loving and he loved Sammi."
Mr Awak said his cousin had made a successful life since moving to Australia as a youngster and becoming an Australian citizen.
He said Mr Piom had adjusted to life in Australia well, particularly since moving closer to his family in Tasmania about two years ago.
Mr Piom had many friends, he said, and played basketball for the Breakers Basketball Club and also assisted with Tasmania's national basketball team, the Hobart Chargers.
Mr Awak said his cousin was not a bad man.
However, he now feared the Sudanese community would receive unwarranted retribution because of Mr Piom's actions.
"When incidents happen we get stigmatised," he said.
"We are not bad people, we are Australian people, just like everyone else.
"We are a kind community, one big family, and we are struggling with this just as much as others."