yes, it probably is to justify his own illicit behaviour he’s been hiding from you. However, heavy coke use will make him extremely paranoid. My partner smoked so much crack cocaine he called me and said someone was trying to get into his flat and kill him. He has also become so paranoid his own sister woke to find him hovering over her holding a knife.
As I said, you have to think of him as two people. Like my partner, I know instantly whether he is himself, an adorable loving man, or the loathsome pitiful junkie.. it’s Dr Jekyll and Mr Hyde.
One piece of advice I would give you.. try to stop ruminating on past good times. They are in the past, and almost certainly won’t be coming back unless he can go into recovery and STAY CLEAN for a substantial amount of time. So reminiscing on the past won’t help you. You have to become stronger now and deal with the man in front of you. And right now that man in front of you has taken money and in all probability, lied to you for some time.