Most Helpful Guy
There is an old song that says "the first cut is the deepest". I can only imagine what you are going through.
Time heals all wounds and in time you'll look back on this guy as the immature jerk that he is. He was treating you badly, cutting you down by talking about all the interest he had from other girls. he was trying to make you feel less secure in yourself - a dirty nasty little control game if I've ever seen it.
Although I imagine you don't feel like dating now, when you start feeling more that way here is my advice for not getting hurt again - don't give anyone the chance. Date a lot of guys but not the same one more than once consecutively. Have fun, enjoy your time, and then at some point you may find a guy that is worth your attention, but there is no rush on that. Finish school and consider college, then when you have your own life you can start getting serious about guys but don't be like so many of these poor girls that get treated like dirt, just keep moving and you'll know when it's time to stop and settle down.
Here's something I heard one time that I sincerely believe: no guy under 20 really loves any woman other than his mother. They could pass a lie detector test, but its only the hormones that are talking. When it comes to settling down and being with one woman for the rest of their life, they are simply not ready. You may be, but guys don't mature as quickly as women, especially emotionally.
Make dating fun, don't let some idiot tie you down and treat you that way ever again. Don't put up with control/jealousy/abuse games even once.