Screwed

I got drunk one night and hooked up with my best friends mother, I felt real guilty the next morning but ended up deciding to be sex buddies with each other, we have been together now for 6 months with no one but us knowing about it, now she is telling me how much she cares about me and she considers me as her boyfriend and wants to move in together, I don't know what to dobecause I like her but I don't live her or anything, and I'm afraid if I broke up with her, she would tell my friend who is also my boss and I don't know what to do, either way I look at it I'm screwed