This week, she came forward to say she's just friends with the star of TLC's Jon & Kate Plus Eight. Now Hummel, 23, is fighting back against her brother Jason and his claims that she really is having a fling with the married father of twin daughters and sextuplets.
"My brother is making this all up," Hummel tells PEOPLE. "He has no credibility ... I can't even stomach the lies he's saying about me."
Hummel continues to deny any sort of romantic relationship with Gosselin, and the elementary school teacher admits that there's been bad blood between her and her brother for a while now. "My brother is very shady," says Hummel. "He has no job. He has a criminal background. He was charged for drug distribution. He's on probation right now."
And though the siblings live together, she says she was in the process of buying their home – and asking him to move out. "He wanted to get back at me ... he knows he's getting kicked out of the house."
Among what Jason Hummel, 28, claims is he overheard his sister having sex with the married reality star. A claim Hummel says "is completely crazy!"
She adds: "I'm so hurt that he put my occupation out there. He has put my job in jeopardy. I can't take my kids to recess without worrying that people will come up and harass me and the other teachers. It's not fair."