Adult fiction book about revenge

I've been looking for this book for years with no luck. I think it is an old book, as I read it in a group home in 2016. Most of the books there were older books.

It starts out with an unattractive and obese, man who manages to land a beautiful girlfriend. I dont know exactly how but he is wealthy. He intends to marry the girl bit then catches her talking to her boyfriend about a plot to kill him and take his money. He escapes and gets into a car accident in the process. Badly injured, He wakes up in a cabin in the woods where a man is nursing him back to health. After several months of living off the grid with this man and regaining his strength/ health and losing weight he decides to return to the real world for revenge. He was able to regain some of his old wealth, and he changes his name. He also takes vocal coaching to fake an australian accent. Once he has completely changed himself beyond recognition he tracks down the ex and her now husband and moves into the same rich neighborhood where he befriends them and proceeds to ruin their lives. I can't remember exactly what he does to ruin their lives but at one point he reveals who he actually is.