My husband had the same, brutal headaches if he tried to quit. What he did was slowly over the course of a few weeks replace some of the beans for the morning pot with decaf, ramping it up until it was all decaf eventually. He’d have green tea the rest of the day. He’s a tea drinker now, but we’ll have a half decaf latte every now and then as a sunday treat if we’re out. It’s really hard to replace coffee with tea as the caffeine types are different.