WHAT IS THE BEST REVENGE!!!?

right, my dad has a girlfriend that he is keeping secret, he had an affair with this woman, they were seeing eachother while the divorce was going through, the whole family had accepted that they were together and we kind of lived with it. My step brother now lives with my step mum and i live with my dad. about 3 months after everyone split up the girlfriend attempted to commit suicide because the divorce hasnt gone through quick enough, and since then (duration of about 6 months ) she has tried to commit suicide again, thrown herself through a gl door which resulted in 16 stitches to the face and also admitted to being unfaithful to my dad on the holiday that he paid her to go on. She has also admitted that she is only with him because of the money that he spends on her. I have had to get a job because of the lack of money in the household, partly to do with the �250 handbags and UGG's that he buys her as well as all the perfume. Now he is secretly seeing this woman again and getting mad when i say that i want to stay at home on Saturday/Friday nights instead of staying at my step mums, i cant even look at my dad without getting angry, anything i say doesnt make him listen..... i just want revenge on the woman. The only idea that i have that is going to happen is drenching her clothes that she has left here, and giving them to my dog that loves to chew things up.... so it would please both me and the dog haha. Any revengeful ideas are welcome.... i plan to use them. thank you x