anal sex wife's mom

i am a 30 year old married man and am presently living in gurgoan. My family consist of 3 members i.e my wife,her mother and myself. We have no kids at present. We lead a good sex life but lately I was having trouble convincing my wife for anal sex and after sometime she got frustrated and complained about this to her mom. Then surprisingly her mother approached me when my wife was not at home and offered me anal sex. she said that her daughter was not ready for anal and in the time being she offered herself to me for anal sex. then one day i did anal sex with her mom and it was very pleasurable. even she liked it . Now we have anal sex everyday when my wife goes out and i too like it very much to penetrate the asshole of an elderly women and its all too good now. i have never had vaginal sex with her mom but we have hardcore anal sex everyone chance we get and i just get a lot of pleasure drilling her pink asshole. Now let me come to my real problem The thing is that i want to divorce my wife and then marry her mom. Her mom is a divorcee. even her mother want to marry me but i we dont know how to convince my wife . all suggestions are welcome and I also request people commenting on this post not to make fun of this situation.I need help badly and i have no idea what to do