well, you have been with her for this long for a reason? Question is....what is the reason? Do you love her? If no, then tear your ass and dont look back. You sound like a cool dude and dont deserve that shit.
If you leave while she is at work then cops cant do shit to you? Unless you do something stupid, and if she reported you missing they wont do shit unless you are gone for 48 hours.....you know this. Its the easiest way for you to justify staying because no one likes change. Leaving will be the best thing for you even though it will be hard and scary at the same time.
p.s. if you love her get counseling and try to make an honest go at it.....IF YOU LOVE HER.