The opportunist

Im not the greatest at relationships. Often times i want to just roam around and not get tied down. That is until i met her...we'll just call her K. K was my type of girl. loved to party was sarcastic and gave me a run for my money. She had issues...she told me in the beginning of our "talking" that she was having a hard time commiting to anyone because of some things her parents did and her x boyfriend of three years kinda finished the job by fucking her over. Im a nice guy by nature with a kinda mean streak about me...but the nice usually wins over. So i try to understand, i compromise...she starts saying how amazing i am...and how she wants to try and make it work with us. we eventually start having sex...spending all our time together...texting every minute of every day. thats when i start to hear things about her. I hear that shes a boyhopper. she jumps from guy to guy and never really settles down. when i asked her about this of course she says "but your different! i havnt cared about anyone like i care about you in a long time. your an amazing guy and i really like you" so i let it go. maybe i am different! i thought. so the days go by and everything starts getting rocky...she wants to stop having sex...only to fuck me again two days later. she all the sudden stops texting as much and it finally gets to "i dont think we should do this anymore. " now ok. at this point i feel a bit lied to. so i start to question her motives...she said she had a fear of commitment...so i try to help...i try to be there as a friend and once again...we have sex and start to hang out all the time again...until she decideds she wants to be alone for a while again. single. she was swearing off sex for at least 3 months so she can get her head together. so i try to be nice and just be friends...but she drops me. she stops texting and calling all together...no myspace correspondance or any gmail chatting we used to do all the time and every time i try to talk to her we get in a fight because i of course ask whats wrong. NOTHINGS WRONG I JUST WANT TO BE ALONE FOR A WHILE...its then i find out the "shocking" news. she had found some new guy to fuck. i found out from one of her friends a few days after we "ended it" she decided to stick a new penis in her vagina. so of course i ask what exactly happened to the "im not going to have sex and be single for a while..." and which point she goes ballistic and starts saying how we were over and it was none of my business what she did. so after a few minutes of arguing and me saying that she was just as horrible as i had heard from countless people...she said that the reason we never stayed together was because "i wasnt good enough for her" and that i can blame it on her issues as much as i want but we were just sex. so...now here i am with a serious case of headspin. i dont know what to do or think about myself or how i feel worthless and alone...my advice to any guy is...heed all warnings...you are not different...she is always going to be the same fucked up bitch she always was. thank you for listening.