His reaction and response isn't unusual, especially if he's genuinely telling the truth.
You've brought traumas, experiences, and trust issues from your previous relationship into this new one. Your first response was to accuse him of cheating.
Things can go unnoticed and undiscovered in places for a long length of time in different places. Things being lost in sofas for years isn't unbelievable.
He could be telling the truth or lying.
Either way the relationship is ruined beyond repair, and neither one of you will view each other the same.
You've lost faith and trust in him an in the relationship. These thoughts will never go away, they'll only expand.
If he was genuinely telling the truth,
You blew it...and he is angry and perhaps saddened by this. You have compared him to other experiences, and it sounds like he was never really given a clean slate.
It's best to permanently leave him alone.
You'll never trust him again...from what you stated about previous experiences...you perhaps never trusted him to begin with.