First of all, welcome to Fiverr… where you will meet all types of people, both toxic buyers, and sellers.
Secondly, you don’t need to reply to every text the buyer sends you (but must reply quickly to the initial first text). You can set your status to “away”… and reply to him once a day. Nevertheless, every hour update is too much.
As for the illegal intent, you’re not responsible for the crime he committed or commits. If you knowingly accepted the gig… it’s on you.
I chat with many friendly people, some scammers (and reported on them), and be open to rejecting some cases for your mental health.
Vent all you want… this forum is for that and like I said… you will meet all types of people. If you choose to continue freelancing, be prepared for that.