My partner is depressed

Me and my partner have been together for 4 years next Sunday. Last week he ended it and said he needed to be on his own for a while because he was depressed and going through some stuff. He said he thinks we can fix this but he just needs some space to sort his head out but he still wanted us to speak. I went on holiday last week in which he was supposed to come but didnt due to the circumstances he said we could speak when I went away but he still needed his space I text him but he told me to leave him alone all week. He said hes been thinking and he doesnt want a relationship right now because he wants to focus on himself. I know he still loves me (he told me this) but he said right now he doesnt want to fix it. He has recently told me that he has been taking drugs because he needs it to help him not lose his temper with people. He told me he owes drug money and he doesnt have it and I am only person he told about this. Today I messaged him and asked him if he was okay as I was worried he said he was but he wants to be left alone for a bit longer and hell speak when hes ready. Tonight we spoke a little more but he just keeps saying he doesnt wanna fix it right now and he wants to be left alone and keeps telling me to go away. I really dont know what to do about this situation. In my heart I know we can fix this and I know its not over but I just dont know how to deal with the situation right now because he wont even speak to me. Advice would be appreciated?!