How do I stop feeling the need to seek attention elsewhere?

Okay, before I expect an answer, I'll go into some detail. I've always been considered a "quiet" person up until I graduated high school. I always have been a not very pretty and somewhat considered dorky girl up until I would say about eleventh grade. I also consider myself a hopeless romantic to some extent. Since I was fourteen, I have always been in a committed relationship never giving myself the chance to feel what it is like to be by myself for a while. Though I think it would be nice to experience the life of a single person, there are also benefits of having a significant other to me. I like always having someone to talk to and to do things together with. But now that I'm out of high school and living in a new town, I've aquired interest from other guys that I never thought I would have a chance with. The only problem with this is, I moved to this new town with my current boyfriend of two years now. I guess I should also say how we got together. Eleventh grade toward the end of the year, I was dating a rebound guy that I was not crazy about, but of course stayed with him because I knew I always had someone to at least talk to and hang out with. (BTW: You're probably wondering why I don't have any girl friends. Long story short, first boyfriend from age fourteen to sixteen completely controlled me and didn't let me keep in touch with anyone besides him outside of school. I never lost all of my girl friends, it's just that two years of not hanging out together really can let people lose touch with one another.) Anyways, there was a guy a year older than me in my one class that I really enjoyed flirting with. One day I got up the courage to just give him my number so we could be "friends with benefits." (BTW: I also am a very curious, sexual person. I know some people wait in relationships but I sort of let that be the first thing.) Of course, what single, eighteen year old guy is going to turn down some fun with an attractive girl that doesn't have a rep for doing things like this. Anyways, a month into it and I fell for him. I really tried not to, but I let my feelings get the best of me, like always. We started to date and everything went well for a year. I never had the urge to purposely flirt with other guys to get their attention. But towards my graduation, that changed. I cheated on him for the first time with a guy that I met once at a party. We texted for one day and made arrangements for me to come over and have sex with him. This "thing" lasted up until October until I had an arguement with this guy. This was all going on as I was now living and still dating my boyfriend. He never found out of this. I believe I would have kept at it to, if it weren't for that person and I getting into a heated arguement. This now leads me to the current situation at hand: In the past month, I met a guy that I thought was absolutely goregous in every way on the outside. He showed interest in me and gave me his number. We started texting and actually even talked on the phone a few times. I did this right in front of my boyfriend and always just called him a "friend." I did not feel guilty because for the past few months, my boyfriend has been texting other girls and being very secretive about it (I don't have a problem with him having girls as friends, I just don't like it seeming like he has to hide it), him not being nice like he used to be and treating me as if I'm a nuiscance (spelling?) to him, and letting our sex life basically go down the tubes. I felt the need to get revenge for all of this and do something that would catch his attention to show him "hey, if you're going to show little interest in me, I'll find someone else." So I had made plans with this other guy and arranged for us to meet up and have sex. It was so good the first time, we agreed to make a second arrangement. I know there is no future with this guy: we both have either a boyfriend or a girlfriend. Plus, he is the typical "player" which I'm a sucker to fall for. My current boyfriend was one, but somehow I made him an exception. Anyways, my boyfriend read some of our texts to each other that I forgot to delete while I was in the shower and found out I had cheated on him for the first time to his knowledge. He left me for two days but came back because this is where he lives and he really has no where else to go. It's been a few weeks since all of this, and we agreed that we are going to work through it and stay together. I guess my only problem is, I really feel that I love my boyfriend, but the only reason I haven't done it again is because I got caught. I know if I didn't, I would have slept with this other guy again. I don't know what my problem is, but I can't seem to delete this other guy's number from my phone. I guess I feel that i