You should not have given in to her and had sex. Your wife IS making sex a miserable experience so that it will eventually end. You need to specifically say that sex is scheduled for thursday nights, and that both partners are to show up with positive attitudes towards a physical evening or don't show up at all.
Your wife is reaching her cruciable. She feels bad to have sex, but she feels rotten for being such a failure in her marriage to you. She wants to transfer that back on you, DON'T GET SUCKED IN ON THIS. Sure she feels bad, SHE HAS TO FACE IT, DEAL WITH IT, OR GET OUT. YOU can not help her with this. You are also in no way responsible for all the feelings she expressed (she was trying to suck you in to HER issues).
So schedule the sex, but if she comes in with a bad attitude, just tell her that you will try again in another week to allow her to change her attitude. It will be hell for a while, so you may have to sleep elsewhere. But DO NOT LET HER TRANSFER HER PROBLEMS BACK ONTO YOU!!!
