Is she really over me?

Honesty is where it’s at. And this is all really simple for me to say behind a keyboard and screen but I’m sure if I was in your, and I may be if things with my ex go well, it would be hard for me to do to. You’ll just have to come up with a way to ask her to be honest with you. The person she’s talking to could just be a thing to try and make you jealous, like a little revenge for NC with her. Everyone’s different and you’ll honestly be the best judge of character for how to ask her.
With my girl, if/when we fix things, I’m gonna lay it all out on the table. let her have the password to my phone, Facebook, everything except amazon. It’s not that its necessary but its more of a sign of trust. Talk to her about how you feel and ask her who the person is. The worst thing you could do is ignore it and let it fester and bother you. You may even find yourself trying to use it as something against her in an argument and she’ll show you it was nothing and all that worrying and fear of her commitment was nothing more than a misunderstanding.
Idk, I don’t really feel like my advice is the best since i’m in a similar situation but anything helps right? All I can say and I know its 100% is build your relationships foundation on trust. It’s key. If you’re not comfortable with something, express it to her, just do it wisely and try not to be accusing.