Help with a movie title...

I've beed trying to recall the name of this particular movie ever since I first saw it in the 80's. It would be considered a "errotic thriller" I suppose. Unfortunately, I can't remember the names of anyone who stared in this flick, so it's been impossible to search for it's name. Any help would be much appreciated. Here goes...A woman is in a bad marriage and decides the best action to take is to kill her husband in order to inherit all the money. She stages a break-in at their house after she murders her husband. She uses what I believe is a bag of potatoes in a pillow case that she swings from a rope to hit herself repeatedly (to bruise her badly) and has sex with a stranger to make it look as if she was raped. Then she strings herself up with ropes and a piano in an elaborate way such that it looks as if it could have only been done by the person(s) that broke into their house. The detectives are pretty convinced that her story is true, but after time, one of the detectives starts to see a flaw in her story, yet becomes involved with her at the same time. Blah, blah, blah.

The movie was on cable in the 80's and has been that long since I've watched it, so I hope I've remembered and described the plot somewhat accurately. This was not be any means an award winning film and I probably remember it being better than it really is, but it is a movie I've only seen once and enjoyed it and really want to watch it again. ANY HELP with the title of this movie would be greatly appreciated!!! Thanks