Kristen/jax text message

I’m watching VR for the first time I’m just on the part in s2 where Jax is showing tom the text message Kristen sent to her as evidence that they did in fact hook up. However earlier in the season we see stassi send the same exact text from Kristen’s phone to Jax when she was trying to figure out if it was true. What I don’t understand is why when this was brought up again why Kristen doesn’t just say- don’t u remember when stassi came over and texted him from my phone?? Instead they talk about her phone possibly being hacked and she’s still denying this ever even happened with Jax. Although I do think they hooked up I’m so confused why this is even a point of discussion, even Lisa asked tom if he believed the text message was true. I feel like I’m being gaslit these people are incredible liars I don’t even know what to truly believe right now