Some People Don't Understand Karma

I never show my true self in the very beginning of my relationships with people; it's been my nature since I was very young to observe people first, then show them who I am. Plus, nobody who just meets me deserves my true essence, it has to be earned. As I went off to college though, I decided to try something different and just go all in. It worked pretty fine for awhile until this guy (who I'll call Charles) started hanging around.
Charles was a friend of my friends and started to instigate his way into our close-knit group. Soon, it got so I couldn't look up and not see him with my other four guy friends. If he was with them and they vouched for him, he had to be a good guy, so I didn't think much of it; I'm naturally friendly and warm to people, and I didn't see any problem accepting new people into my life. Until one day, he approached me romantically and I rebuffed him; I was interested in a certain King of Confusion at the time and I didn't want to pursue anyone else, no matter how hard they were pursuing me.
Suddenly, all the information (confidential, girl talk information he'd gotten from hanging around the women of our group) he acquired was turned on me in a negative way. Every time I rebuffed him after that, he'd slip out a tidbit of information in the wrong way or say something hurtful. For instance, I'd maybe go and hang out in the parking lot with the King of Confusion and the guy would say something snide, insinuating more was going on than really was, painting me in a shade of harlot.
I'd had enough of him in time, and ended up telling him he and I were no longer all that; my loyalty lies with those who are loyal to me, and he certainly wasn't. Soon, he began doing to my friends what he'd done to me, hurting them on purpose but always with a jovial, friendly attitude. I warned them that he wasn't who he pretended to be, he was not their friend, and if they didn't heed my warnings they'd learn that the hard way.
I hear he's now doing something sordid behind my best guy friend's back, and it pains me not to be there to tell him off. How dare he? We were his friends, we were there for him whenever he needed, and he goes and does something menacing and hateful to the one person who accepted him the most? Then I realize, it's not my place to say anything to him. My Gram would tell me that what you put in the world is what you get out of it, and I firmly believe that, so in time, he'll reap what he sows.
Sometimes I forget that all people don't come to you with honesty and good intentions. Some come to hurt you or use you for their own selfish gains. You'd think being fresh out of high school that would be engraved on my brain, but as it turns out, until recently I always put such faith in the good in people. What's a girl to do when the good in people is hidden under so much malice and wrong-doing? This girl is going to keep seeing the good, but not denying the bad. This girl is going to realize when it's time to keep it moving when someone in your life purposely hurts you. This girl is going to go on living her life...just not talking about it around everyone :) .
XoXo,
Testorshia D.