Normal Asked: How can I lose 15-20kgs in a month? READ DESCRIPTION?

Well, my parents are flying up in 1 month and they have not seen me since my wedding day 2 years ago when I weighed 136 lbs (60kg). I have known about this visit for about 4 months and I have dessperatly been trying to diet and excercise but the longest I have lasted is 2 days before I just break it. My parents have seen my face on video chat ect. but I do not have chins or a fat face, it's my torso and the tricky bit is they want to go to the beach!! Now I weigh 190 lbs or 86kgs and I have a belly, moobs and thighs!! Can you please improve my diet and exercise remembering I DON'T EVER eat/drink alcohol, soft drink, energy drinks, pizza or meat!
My diet:
I wake up in the morning and As soon as I get dressed and packed ready to go, there's no time for breakfast and my wife is out on a jog so she can't lecture me about it's importance. I just brush my teeth and grab an apple/ banana ( eating in the car ).
I work as a phycologist, so a work day is 8am – 5pm. My wife owns a clothing store, so she usually works 9am – 6.15pm.
By the time lunch comes around I'm so hungry I am dying for fastfood. I will rarely go for subway but Usually I willeither eat at mcDonalds, getting 2 large fries, a salad and a shake or at KFC getting 2 large fries and a krushie. i will always get some kind of Chocolate shake/ smoothy with lunch. I will stop at the super market to buy a packet of lollies to snack on for the rest of the work day.
When I get home, I am so hungry that I will eat anything. usually I will start with Sweet biscuits (usually NOT chocolate) then I will have some ice cream and a chocolate bar (Which are all hidden in my closet exept for theice cream). When my wife gets home she will tell me to get dressed in my track gear and we will Go for a walk.
After the walk we have dinner. Dinner usually consists of some healthy "low fat" vegetarian dish (full of vegies) my wife will cook me, because she's a health nut!
For desert my wife will only allow me one piece of fruit (she's very fit and healthy). I will late night snack though. I will get up at around 1am (usually 2 hours after we have gone to bed and she has fallen asleep) and I will snack on sweet biscuits, (usually NOT chocolate), savory crackers and I may have an ice-cream sandwich or 3! Sometimes I will also have a piece of fruit if I feel bad. On Saturday's and Sundays, I will usually go out to McDonalds at 2am and order a large fries and two ice creams because my wife is home half the day on Saturday and all Sunday, so she makes sure I am strictly eating ONLY healthy foods and I am doing exercise.
Don't give me crap like "you're fat" or "follow your wifes diet" because I know I am fat but atleast I eat healthy foods and my wife eats meats in most meals included in her strict diet and I am vegetarian. Just tell me HOW to lose around 20kgs in month. I will probably put it back on before Christmas because I am actually quite happy with my lifestyle and I have maintained my weight of 85kgs for over a year and my BMI is 29 so I am not obese.