At first I should explain a bit the situation:

Dated this girl for 2months, broke up just 2 weeks ago, but get to see her every day at work, without even talking at her. At first she tried talking ,but after just getting a straight look in the eyes stopped trying. While with her and still now am dating a girl that plays very difficult and that wants a ltr(I want that too ,with her) and another one that fucked casually but that isn't even attracting to me. Now it's been 10 days I ain't fucking and want so badly to fuck again the ex I have at work. This is where the question begins:

I shaved my head ,cause am going bald and she sees me at work like every day.I saw her and passed like always, like I don't even know her(at work none knew we were together, so none looks me as a weirdo, except her maybe). She noticed my new look and texted me:

Why did you shave your head?

I haven't replied cause at first just thought fuck her, I am not going to deal again with her. But now I am thinking that I want so bad to fuck her, because the one I fuck casually may come ,but I can't even get hard with her.

So how do I reply now?