In your situation I'd go with the breaking-up routine, which I have modified to great success in the past:
Fake fight with her over something. Find something small and fairly innocuous to disagree about. Once you have found the item, tell her that you are breaking up with her. If she seems to be enjoying the game, start describing how you are going to divide up the various items you own. Keep it light and funny. I will often say things like, "Naturally, I am going to take the dog, but you can have the morgage payment." Get her involved.
Up until this point it is a fun way to build some attraction and also break rapport. Also this is the standard break-up routine/game. Now comes the part where I like to take it sexual (this works really well if she has been having fun up until this point and joking with you.)
You: "Well I guess it's really over."
She: (a response. Best if she says something about how she is going to miss you, or otherwise expresses some fake regret)
You: "Well actually, I was really angling for crazy make-up sex, but I guess that's out after you caught me with the maid. :P"
At this point you have given her a chance to turn it sexual, but you have also kept it not too personal and given her an easy way to say no as well. If she is in to you, and possibly entertaining the concept of sex, she will likely say something flirty or joking. If she does, you start talking about the sex. I like to start by asking her, "Hmm, bedroom, or kitchen? The bedroom is more romantic, but the kitchen could be sexy!" Now you have lead her into a conversation where it is safe for her to discuss having sex with YOU, and also you will be turning her on.
Last girl I tried this with started talking about how we really should get a three way going with the maid! In the end we were talking about how she likes sex, and then I started describing exactly how I would fark her, and she was also giving me pointers and contributing. This went from a txting conversation after I had seen her once in real life, and we were talking about something mundane like pizza toppings, to us setting up a date to get together and fark.