The fight against Hellewell was the first for Gallagher, from Luton, since her mother-in-law Diane Cleary was murdered in January.
“The only thing she would want me to do is carry on and chase my dreams,” the 27-year-old said.
“She was the biggest supporter. Saturday night, she would have lost her voice like she did every single fight, screaming and shouting for me. I had her voice in my head the whole time.”
As well as her ring career, Gallagher is also working for the Boxing Saves Lives charity in her home town, trying to help young people stay away from knife crime.
“If children aren’t feeling confident, or they’ve got low self-esteem, they want to feel like they want to belong somewhere and sometimes in gangs, that’s where you feel like you belong, but there’s a lot of other places where you can belong and create a family, like boxing gyms or football clubs,” she said.
She added: “I was the class clown. I always had my wits about me but I was easily led, easily distracted and if I wasn’t in a boxing gym every night after school, where would I have been? What situations could I have got in?
“Boxing took me away from it all. Boxing has saved my life in so many ways and it has made me ready for tough situations in life.”
Tysie Gallagher was speaking to BBC Three Counties Radio’s Justin Dealey