I just skimmed through the requisite arguing that occurs on every post longer than three replies, and didn't see this perspective offered, so here it is. Regardless of whether or not the insurance is a good deal financially, you may be getting more than money from it.
In my experience, there are two types of salespeople in the world, the kind who is looking for a quick buck, and the kind who has drunk the Kool-Aid and truly, deeply, believes in their product and cares for their customers. It is so obvious to them that their product is a great value, a wonderful product that can greatly enhance your life. They genuinely care about you, and believe that buying their product will better your life. They worry about you when you don't buy it.
When I met my fiance, he was broke, sleeping on the floor in the dining room of one bedroom apartment, behind on every bill, but paying 90$ a month for the privelege of selling legal insurance (you pay X$ per month, and if you ever need a lawyer, their rate is reduced by a percentage, based on how much you are paying). He had never made any money, but he believed in the product. He still, after reading most of MMM's site, and learning to make far better financial decisions, believes in the product. It will always be a bone of contention between us that I forced him to quit. I basically gave him an ultimatum after we'd been dating for awhile, and I got a look at his financials. As soon as you cancel that policy, your MIL may be fraught with worry, because she believes in whole life insurance. If she's that type of salesman, her first priority will be to help you rectify this mistake, because she cares about you and wants you to have this amazing insurance. You may have to say no a couple hundred times, and hurt her feelings pretty badly. Just a thought.