Hi Tammy you sound like a pretty understanding person and he is lucky in a way.
The dating site thing like others have said is more of an outlet IMO.I have done that myself but I was not in a relationship.
I do have an issue with you "finding" his clothes stash and going thru his phone "finding pics" Honey that is called snooping and not a very nice thing to do.How would you like him snooping in your stuff trying to find "dirty" little secrets? Shame on you.
He is scared and at 24 being "outed" is by far the worst thing that can happen. He will lose friends and possibly family if they found out he likes to CD.
He is in denial and will do anything not to be discovered.
I have had partners snoop in my stuff and it has caused me to walk out on what could have been a great relationship.
Good luck breaking the ice because it looks like he doesn't trust you either and can you blame him?
I hope you two can work things out I really do.