Hey Trish...
I've been in a long distance relationship, a VERY long distance relationship (Canada-Egypt) for more than four years. It ended in just the last two weeks or so, and it didn't end well. In fact it was terribly painful for me and I'm still trying to recover from it.
The paranoia and insecurities you mentioned in your post were EXACTLY the concerns I had in my relationship. At some points it got so bad I would just phone her up just to see if some guy would answer the phone. I didn't handle my insecurities well, however I was able to overcome them because the one thing we had that is absolutely critical in a long distance relationship is trust. If you do not completely trust your partner, and you are prone or vulnerable to insecurities, I would cut it off immediately, otherwise you risk having to deal with a lot of mental anguish.
If you are serious about making the relationship work, I have some other advice for you. First of all, one of you is going to have to move. You need something to work towards, to progress the relationship, otherwise it won't go anywhere. In the meantime, however, both of you are going to have to make plans to see each other, ie. you travel to see him and he travels to see you on a regular basis. This might sound redundant to you but I can't emphasize how important that is to build trust.
The single biggest problem I had though was dealing with the insecurities you were talking about. Sometime it would drive me crazy wondering if she was cheating on me. You have to talk and be very blunt with each other. I can't emphasize enough if you don't trust each other completely it will be extremely difficult to make it work.
A long distance relationship is very difficult to make work, especially the farther away you are. I was SURE that I could do it, but despite my best efforts it just didn't happen. I hope things work out for you, and hopefully what I've said can help educate you.