Run. For everyone's benefit.
If you cared for her and wanted to help it would be one thing, but that doesn't seem to be a commitment you want to make.
If something does happen to her becausw of you, that's on you for life, people will remember that shit.
Find another fuck-buddy, and move on, hopefully she does too.
But having dated a girl like this forever long ago, the longer you lie to her, about anything, the worse things get, and this looks pretty bad already.
You.... You watch the rest of the movie there bro?
Cause it's not Avatar.