Drink more?
No, seriously though. Being dehydrated to the point of hospitalization must've been horrible. It would take a long time for your body to feel normal again after reaching such an extreme state. Never mind undergoing a serious change to your system by going off weed. Good for you, sounds like it's the right time for you to make a change.
You've been a habitual user for a long time. It will take some time for your body to adjust to being off weed, detox symptoms can include anger, headaches and insomnia. Give yourself some time, it absolutely will get better after several weeks, realistically maybe a couple of months, until your body regulates itself again. When rage hits, take a deep breath, remind yourself your body is going through a change, don't take the anger personally, remember it is temporary and will get better (though not overnight), and it's for your personal betterment and health in the long run and therefore worth it. Then take another deep breath. In general, drink more water and try to get as much sleep as you can.
I don't blame you for flipping shit over stupid things - people are dumb and much of what happens around us is beyond our control. All I can offer is this: one's energy is a precious resource, especially so when you're sick, and being angry takes up a lot of energy. It's just not a productive way to spend your time, so choose to spend those energy points on other things.