You asked if it is not true or just an ad hominem. They listed why you might suspect it to not be true, but that we can’t know for sure (just as you can’t disprove a god, because you can’t prove that something that doesn’t exist doesn’t exist). You’re then angry at them about that? Fuck right off. You’re a dishonest person engaging in a bad faith discussion. Everything they said is relevant to why you’d question their authenticity.

An ad hominem fallacy would be saying she’s a bad person in a way that does not materially effect the discussion. It is to short circuit it and make it so you don’t have to engage the facts. While this might be an ad hominem, it isn’t fallacious. These are materially relevant. It’s not just saying she’s evil, which she could still be telling the truth regardless. It’s saying she’s previously participated in actions that you’d expect from someone who would make something like this up.

It’s like if someone drinks all the alcohol, then a drunk alcoholic claims it isn’t them. Bringing up the fact that they’re drunk and an alcoholic isn’t fallacious. Sure, it doesn’t prove they drank it, which will probably be impossible, it does provide a reason to be suspicious of them.