If I were to put myself in the model's shoes...I'd be creeped out and annoyed if I found out there's a forum thread from a member who's admitting that he's been trying to hide from, while also telling everyone that he "ended the relationship." Lol.
As it was already suggested to you by Vixxen, the model may have figured it was you because when you interact with her...you have mannerisms that are different from the other members she converses with. That doesn't necessarily have to be a bad thing. I mean, I would think you'd even be a little flattered that she knows you well enough to tell that it's really you. Unless there's something you're not telling us, and the real reason you're hiding from her (and posing as someone new) is that you said or did something to upset her? If you
didn't do anything to upset her, then it's just really strange to me that you are going out of your way to make sure your model "friend" doesn't know it's you.
Sometimes it could be as simple as the tip notes that you leave for a model. If, for example, a member has a habit of including "Luv u, princess" (*cringe*) with every tip note, that could be one thing that gives you away.
If I got a text message right now from a phone number I didn't recognize, and it said "Hey baby girl. How are u," I would immediately know which ex it's from, because "baby girl" would give him away...