I would use one fourth of my money to ruin her completely. Vengeance is the best thing ever. Use your wealth to get all of her friends on your side, until she has no one. With the rest of your wealth, invest in stocks and increase your wealth, and with that accumulate more power. Meanwhile your ex will die alone, friendless, at an early age due to her rampant alcoholism. Hahaha
OHHHHHHHHHHHHH SNAP!