short answer - typical drug addict behavior.
longer answer - if i read your post correctly, YOU broke up with HIM.
so I decided to end it. he then cut you off, which is kind of what happens when people break up. again.
from what you share, he's never been "clean and sober" and it sounds like he is also doing some type of stimulant - coke, meth, adderall, etc. weed doesn't make people erratic and off the charts as you have described.
so let's do some math - known each other for 9 months, or 36 weeks.
broke up for 7 of those weeks, so 29 weeks. only see each other every couple of weeks (5 hour trip each way, mostly you doing the traveling, on your own dime), so have only been in F2F contact during 14.5 of those weeks. sounds like mostly weekend trips/visits - so 14.5 weeks = 101.5 days, of which you have spent actual TIME together of maybe 29 or so days.
i'm curious why at the tender/young age of 22 you are chasing someone around like this? going to extraordinary lengths to go see someone that requires TEN HOURS of travel for a couple days every few weeks? someone who is a confirmed drug addict, with a side of gambling addiction, who is moody, inconsistent, and treats with you disrespect?
this is not really about him. this is the time to ask yourself WHY this is the path you chose? if you looked up Emotionally Unavailable in the dictionary, i wouldn't be surprised to see this guy's picture. and as you have stated, this isn't your first rodeo with a drug addict.