How do i move on already? is it bad to get even?

wow, do I feel like an idiot!!!! I wrote on here about 4 months ago and so much has changed….it sucks because looking back and reading what I wrote, I new in my gut what I had to do. mid way through May, my girlfriend was the one to break up with me. I wasn’t shocked, and its not like it came out of know where. I mean things truly just weren’t working, but I wanted things to change and I wanted to at least try and make them work. In my eyes I was the one who suffered more. I only fought with the girl because I never saw her, its like she was my girl for almost 8 months and yet her parents didn’t even no we dated. I never had a real relationship with the girl, and I always envied other kids relationships. I always laughed at kids when they would beg for a girl back or trip so hard over ONE girl. I didn’t beg for her back, but I wont lie, I was pretty desperate. I just couldn’t believe after all year long, I wouldn’t get a chance come summer time. I truly thought I was going to win her back. Now its basically the end of summer and I just feel like a fool. I made a fool of myself, I just didn’t want to accept that this girl truly could give a fuck. I didn’t think she would turn her back on me the way she did. I was nothing but sweet to her and for the past three months all I wanted to do was to try and see her. She wouldn’t, she wouldn’t give me the chance that I disserved. it’s a JOKE though because im only 17 years old, I no Im not going to marry the girl and I know I wasn’t in love with the girl. So why am I beating myself up so hard? And I don’t get why I would even want this girl back when I wasn’t even happy in the first place? I feel like a fucking idiot, I cant believe how stupid I made myself look. And I still seem pathetic to her because even now I still go out of my way and text her and just make myself look even stupider, if that’s even possible. I feel like iv grown up so much this year, but yet how im handling this, it makes me feel like a little boy. I said to her recently, “I don’t get you, you act like I did something so terrible, you act like I cheated on you, iv been nothing but nice to you, I just wanted to see you more, not NOT see you at all, you wont even come see my face…..” but first off this girl would tell me, “we have all summer to see each other…” and she told me several times “ohh well hang out soon, when I come home next week…” and then she would just blow it off, and made me feel like a fucking fool. So heres the bad part. I hooked up with her BEST friend, ahahah yeah that’s really bad and immature and I know it myself. But its like what the fuck, I was so good to her and I was so sweeet to her. She played my ass and made me feel like a fool. So yeah I kissed her best friend and she doesn’t know yet. I want to put it in her face so bad you have no idea! And say “you no what, you told me you would come hang out so many times, you were my girl for 8 months and all year long, and when summer came you couldn’t give me five minutes, its like you erased me from your life for no reason, you made me feel like a fool. So yeah I kissed your best friend, and you no what, now you have a fucking reason to be mad at me, now you have a reason to never talk to me.” its like I only did it out of spite, which is so wrong, and I feel bad because now I fucked over their friendship, but hey, any girl who would do that to her best friend isn’t a good friend at all. Should I say something to her? Its like why shouldn’t I though. I know its so immature but its like I was SO FUCKING GOOD to this girl, and its like she continually slapped me in my face for no reason. I just want to tell her so I can feel like now she has a legit reason for doing what she has been doing all along. Its like fuck man, karma is a bitch. And this is hers. Maybe im just blind and im completely wrong here. Maybe I should be the bigger person and keep my mouth shut. What do you guys think? I’m sick of feeling like a fool and im sick of still thinking about this girl, specially when I no there are a BILLION girls out there. What do you guys think???? Should I say something??? I really want too…but il take any advice I can get at this point………