Four boys involved in the abuse in Bransholme have now offered personal and written apologies to Ms Sipa after Humberside Police arranged a restorative meeting.
The youths have also voluntarily picked up litter in the community as a further gesture of apology.
The officer in charge of the case, PCSO Kay Newton said: "She was able to get across to the youngsters just how hurtful their behaviour was and how it has affected her quality of life.
"She mentioned that she was fearful her flat would be set on fire."
Ms Sipa first called police in November when a group of girls started banging on her windows, before kicking her car and causing damage to the rear headlight.
A week later, when she got home, three boys were standing outside her window, shouting abuse, including , "When are you going to go back to your own country?"
They continued to abuse her, kicking her front door when she got inside.
PCSO Newton said: "The offenders discussed with Anna how the incident was not about her being from another country but that was just another comment they made in their frustration – and one they regret.
"Following this, parents of the offenders said that the letter alone was not enough for what they had put Anna through and it was decided litter-picking would also be carried out in their local area for everyone to see them."
The boys carried out their litter-picking duties on December 15.
PCSO Newton said: "I have spoken to all parties recently.
"Anna said she was pleased with how the conference had gone and that she has since seen some of the boys on the estate, who have said hello and been very friendly.
"One of the parents said her son was upset as he had not realised just how bad they had made her feel, and the comment about her worrying about the house being set on fire had particularly struck home with him."
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