Ha, you didn't trust him, went through his stuff, which demonstrates exactly why you don't trust him!
The thing is, you don't have to listen to any of his reasons, justifications, blaming of you, etc etc. You have seen the text saying he isn't happy, you've seen the creepy sexual flirting, you've seen him accept your money, your roof over his pathetic head.
Just say you know when you know, like a stick record, and do not be drawn into anything else.
Then unfollow and block him on Fb, and don't look back.
Sorry he had treated you like this, but luckily you found out before he did worse damage.