I'm so heartbroken someone could treat me this way. I am contemplating going to his place today unannounced just to check on him and to try to get my things.
Please listen to those above who wisely suggest that you do not go there alone. You may have no idea how dangerous this situation could be for you. Drugs make them crazy, no matter what they were like before drugs.
Having police with you if/when you go would also protect you if something has happened to him.
Whatever is going on with him is not your fault, not your responsibility to investigate or try to change, and very dangerous territory for you to consider entering.
It hurts to let go of someone we love, but the sad thing is that we are holding onto "what might have beens" and not "what is" at all. When I let go of my son's addiction and turned his care over to God, I was letting go of the person he used to be. The active addict he was had left my contact a long time ago. Thinking I had any control at all was an illusion that kept me in Crazyland long after I should have taken myself to someplace safe.