You get pulled back in because you allow it. He knows how to suck you in and he has done just that once again. You are back in this cycle because you slept with him a few weeks back. Now he thinks he can convince you to do so again. You deserve so much more than what you are getting from him.
I think you need to decide where YOU are in all this. Are you ALL IN or are you sitting on a fence? All In means you are living your life while doing nothing to make it impossible for your spouse to return. That means no dating, no illusions of dating and no game playing which are all indicative of fence sitting. It also means that you have to respect yourself enough to not allow yourself to be used.
You can be All In, stand for your marriage and not sleep with him.
*hugs* ~ swl
Look not mournfully into the past. It comes not back again. Wisely improve the present. It is thine. Go forth to meet the shadowy future, without fear. {Henry Wadsworth Longfellow}