welcome to pc
I agree with cantstopcrying

I wanted to say, that regardless of the outcome don't feel dumb. Especially online, people can fool you without you noticing. I had an online friendship that turned sour - he wanted more... I look back and he didn't even mean to completely, but at the same time he did.
What I'm saying is, especially online and also in normal situations, unless something is clearly defined there is a possibility for misunderstandings and it's NOT YOUR FAULT. Please, don't blame yourself.

Regret, but lay no blame.

As to what's going on, I can't know. I don't know him. I like cantstopcrying's ideas, of approaching him. Maybe taking the sex out of the picture would be good for you. It's obviously upsetting you right now, and if he really cares for you he'll be ok with it (sad yes, but ok) and if he's just using you... it may become apparent that this is so

just please realize
what happens between the two of you does NOT define who you are
YOU are not bad
YOU are not stupid
YOU are NOT just a sucker
Having sex for the first time - everyone wants to know what it's like so bad. It's not just a mental but a physical pull. You can't blame yourself for wanting it. You cant blame yourself for taking someone at their word. You based your decision on your past experience (erm... no boyfriend before so yes possibility of silly mistakes again NOT YOUR FAULT)
You've done your best in the situation.
Keep doing the best you can.

hugs hugs hugs
I hope all goes well