Hiya invisiblegirl. I understand what you're saying. To paraphrase for those who haven't quite caught the subtlety, the anonimity of the internet can be very liberating when you aren't yet sure of where you belong.
As my girl indicated, there can be some real tossers out there (and some very nasty predators). The best thing you can do is stay true to yourself, and stay safe. Talk on-line, chat on-line. Follow up by reading what the people you chat with have written on this site (or elsewhere). Get a feel for the people you chat with, run away from those who tell you to disregard your feelings of unease and "trust them".
A little suspicion/paranoia can help keep you safe. And any dominant (or submissive for that matter) who is worth his/her salt will understand that you will tread cautiously until you feel safe.
Good luck in your search for who you are, and I hope you have as much success in your search as my girl and I have had in ours. We started on-line too, and have been real-time and married for a while now.