I'm a bit confused OP. You wanted to do cyber stuff with him in the moment, right? Or did you feel pressured?
I just think... is he necessarily a creep? If you were game and he was game? And what's wrong with that happening?
Sure, maybe he's married or just wants sex (doesn't make him a creep, unless he's pretending he also wants a relationship when he doesn't), or maybe he's just horny like a lot of people are and you both just got carried away in the moment, or whatever.
The way I treat online dating now is like speed dating. I put up a quick profile, I don't overthink it, I swipe and chat and see if anyone wants to go on an actual date, and once I start feeling desperate or bored or disillusioned with the whole thing, I delete my profile. I only ever use online dating when I'm in a happy, curious mood. I look at it like I'm walking into a bar and just chatting people up. This stops me over-investing in weeks and weeks of talking and getting wrapped up in fantasy.
You haven't done anything wrong. He hasn't necessarily either. Meet him if you want to. Communicate with him if you want to, and tell him the whole penpal thing made things move too fast, and you'd like to start from scratch. It just depends what you want.
In future, I'd just recommend that when you connect with people, you don't agree to exclusivity before you've had at least a few dates, and you just talk for a few days then meet up. If they're on a trip or busy or not available for a while, there's absolutely nothing wrong with saying, "No problem, let me know when you're back :)" kinda thing. Talking for weeks beforehand builds false intimacy, and it's really easy to be uninhibited when you're connecting through a screen where everything can be perfect/exciting/fun.