Cocaine induces mood swings, specifically triggering depression. His mental health will improve when/if he stops the drugs.
The thing with most addicts is that they chase the highs, and avoid the lows which is why they take so much of this stuff and it leads to heavy use.
In my opinion cocaine will always win hands down, now he may well come back but what version of him comes back is anyone’s guess. You sound as though you don’t want to lose him, and what’s more worrying is that you want him to come back, despite what his putting you through.
Do you think you need some space now. Have you spoken to anyone else about what’s been going on so you can get some outside perspective? I don’t know you but I do think you’re a wise young lady.
You deserve better than this. Remember it is the drugs that influence his behaviour, but they do have choices and are fully aware of that.