I noticed that you hadn't been around! I'm so sorry to hear about the SO. I've known a few Dr.Jekyll-Mr.Hydes, and your insight is right: these people need weaker ones around to feed off, and to take their crap when they choose to dole it out. You're lucky that you decided to go on holidays together so soon, and saw his dark side before you got in too deep.
Hope you're doing ok! Breakups (even when they're for the best) split the world open a little bit, and make us question and doubt everything.
"I think the basic anti-aging diet is also the best diet for prevention and treatment of diabetes, scleroderma, and the various "connective tissue diseases." This would emphasize high protein, low unsaturated fats, low iron, and high antioxidant consumption, with a moderate or low starch consumption.
In practice, this means that a major part of the diet should be milk, cheese, eggs, shellfish, fruits and coconut oil, with vitamin E and salt as the safest supplements."
- Ray Peat