The rumors that the Shi family kept spreading were targeted at Shi Jin, but also put the Li family in an awkward position. If the Li family was made a laughingstock, they would never be able to hold their heads up high in town.
Shi Jin did this so everyone would know that the Li family didn't sell their daughter for money. She had also ensured that everyone knew about what Yu Xiuhua had done.
If they allowed Yu Xiuhua to go on spreading this nonsense, it would be much harder to clear the air in the future if this was left to fester.
After Shi Jin hung up the phone, she said to everyone, "The Shi family doesn't like having me around and I am genuinely not their biological daughter, so I will sever ties with the Shi family from now on."
Since Old Master Shi has brought me up and treats me like a real granddaughter, I will not leave him in the lurch. I don't care about the rest of the family, but I will continue being filial to him."