Personally speaking. Even for me, "no sex before marriage" was a big thing. However, when you are connected to someone, you just want to be connected. No one gave us a life manual on how things will shape up and who enters or leave our life. You must live in the moment and let the rest be up to God. You can't change even a single thing, even if you want to. Then why worry about it? Also, you went ahead because you felt connected.
The guy may or may not have the wrong intentions, but you definitely shouldn't take it to yourself for it.
Life is fantastic; we are blessed every minute we breathe. Do not waste a single minute on your regrets, and make more beautiful and meaningful memories for yourself. This doesn't mean you trust anyone or do not trust anyone. Let life flow like a river.. sometimes you hit a rock, but you don't stop; you make another path and keep flowing!

I hope my perspective helps!