Mental breakdown is a very broad term, just like the old equally broad term Nervous breakdown (which is still in use) and, as others have said, you really need to see a therapist or a mental health professional to get a proper mental health diagnosis and treatment. We're your peers here, not professionals, and while we can certainly empathize with your feelings, we can't tell you that schizoaffective disorder that needs treatment by X, Y and Z medications.

From the description of your symptoms, it sounds, for instance, as if you have trouble controlling your anger, as if you have problems with anxiety and as if you have depression problems. There are probably forums on this board for all of those those! Instead of trying to treat each feeling on your own, a good therapist would probably look to see if there's one diagnosis that 'fits' all of those symptoms. I didn't look to see where you live, but most counties in the U.S. or most councils in the U.K. have "crisis centers" where you can go if you feel as if you're actually in the midst of a mental breakdown.

There may also be national hotlines that you can use if you feel if you're in danger of self-harm. I've never called one but I've never heard good things about them.

There are chat rooms here but I don't know how to use them.

Just keep on going, keep on here, writing as often as you need you until you get professional help.