You know, your post just know made me think of something else as well. I think it is really important to get to know more about addiction.
As you describe him he has all the hallmarks of an addict (generally). He is angry and defensive - check, - Shame (this is common in general with addiction) - check. etc
So yes, he is a good guy and I'm certainly not going to say that you didn't spend that much time with him, relationships are what they are. You two spent a lot of time together, probably a lot of time talking, some really meaningful talks and that may well be the draw. Addiction is a self centered pursuit. He probably spends a lot of time thinking about his demons.
But you know that's not enough, that you don't want to be involved with an addict.
So perhaps, always remember, when you think of him that he is an addict. Is he getting help? Maybe. Is he recovered? Doubtful. All those things attributed to his addiction are still part of him. It can take years to unwind all of that. Defects of character. So even if you are holding out some hope of reuniting, remember that would be at least a few years down the road once he has had help and really done the work.
Also, he wasn't been truthful with you, he took your money to go buy you something when you were sick and didn't buy the goods and didn't return your money. I'm sure you have forgiven him for that, but that was just one lie.
In a nutshell what I'm saying is that it may have been easy for him to be semi "normal" under the circumstances you describe. The summer, a beach. But that, as you know, is not all he is. When you think of him, try to think realistically. He is a grown man whose parents had to take his phone and wallet away, they know him well.