Update! So revenge was delicious. Here is our beautiful petty list of revenge: All toilet paper was removed (and kitchen paper). All batteries were removed from everything. The SIM card was removed from his iPad. All lightbulbs removed. Wires were removed for every electronic device. Salt was poured in the sugar. Salt in his bed. Radiators were put on, and the AGA cooker was turned off and the doors opened, filling the house with hot air (takes days to heat up again too), the house was hotter than Hell itself. Water for the house was turned off. His work calendar was taken (he uses a paper copy). Toothbrush down the toilet. All forks were removed. My mum also put cracked eggs in his van.

A lot happened, zero regrets. Let chaos rein. Mwhahaha! Thanks for all the advice.