As I am reading your post, all I can think of is my 10yr old niece that I have custody of. You are DEFINITELY not alone! I have had custody of my niece now for almost 4 years and we are at a point that it is starting to semi get better, but every 6-8 months ON THE DOT she has a big episode. Please talk to your doctor or psychiatrist about possible Major Mood Disruption. It is the child equivalent to Bipolar. It is almost impossible, it seems, to get a child diagnoses with bipolar as I have seen may psychiatrists with my niece about this. She does the exact same things you said your child is doing. Sadly, my neice has been hosptalized multiple times. She has a lot of other factors that come into play with her diagnosis. To start on paper we have the following: ADHD, ODD, MMD, Lead Poison, and PTSD. I honestly believe she has schizophrenia as well but no one will entertain the idea. (She tends to hear voices).
Honestly, I can’t say it will get better. But once you get in the right direction of getting some help for him. It can get easier. You can get opened up to a whole new world of help once you get the right diagnosis. In my case it has gotten easier throughout the years I have had her. Also keep in mind, I have 5 girls I care for. 3 of which are my own, ages 2, 5(ADHD and ASD), 6(ADHD,dyslexic, and Generalized Anxiety), and my two nieces, 10 (All diagnosis listed above) and 11yr (Depression and Generalized Anxiety).
Life can get easier which can make it better. This parenting thing is hard. Very hard. We are all just trying to make it each day.