My wife got me a Mistress

Both my wife and I have careers and our career are booming. I'm 37 and my wife is 36 and we've 3 young children 6, 4 and 1 and as our careers are taking so to speak. My wife decided 3 was enough and I agreed, she got her tubes tied and I was going to get the snip. But my wife said don't bother, but due our careers sex became less regular over time. I really like sex and my wife knows that and so she arranged for our live in housekeeper come nanny to provide me with sex. The housekeeper is 54 and my wife's mother (widow) similar in looks to my wife only more mature looking. So, I fuck my mother-in-law when I'm horny or she is. Mostly me and we have threesomes with my wife regularly when she is home. Her mother shares our bed every night whether we've sex or not. It works for us and I'm quite happy with arrangement. My wife is starting her our firm and wanted me as a partner, and I accepted. That will mean we're together more than we have been for a while.