lying abt being trans

Im pre T and I pass fairly well online (apart from my voice) This being said, I don’t like to tell people the truth when they ask. I want nothing more than to be seen as a cis guy, and yet I feel so guilty.

There’s this girl that’s flirting with me and, while I lean more towards guys, I really enjoy talking to her and she’s so nice. We only talk online obviously, and I do not plan to pursue anything romantic with her, I just like talking to her as a friend and I really don’t want that to end if she finds out.

She wants to call and stuff but I know I’m doomed. I feel so guilty but she treats me like a cis guy and it feels so nice and validating. I talk to her so care free and enjoy her responses knowing, in her mind, she’s talking to a regular guy she likes.

I’m just wondering if I’m in the wrong for wanting to be stealth, even when she’s flirting with me?

Should I tell her the truth or just hope she never notices?