You were young and stupid at the time, and to be honest you still are. All 19 year olds are. You'll grow as a person and the guys you end up dating will also have grown as people and be able to accept that everyone makes mistakes in their past. This guy was a lemon, but the next might be the one. Don't give up, don't hate all men, don't hate yourself, just try to be the best you that you can knowing that not everyone is going to accept you and that that is ok. Usually accepting that not everyone is going to love you is something that comes with age, so I get why at 19 you are so hurt by this. But you will be ok.

That being said, you will meet people up until they day you die that believe "once a cheater, always a cheater" and therefore will never trust you in a relationship. This is ok, it just means you are not compatible with those people. Find someone who doesn't care about your past and trusts that you have changed. Just be sure that you actually have changed.