Help?

Alright. Well I'm 17. and the girl I'm in love with is 16. Ill just start from the beginning.
I met this girl through some friends beginning of April 2010. talked like a day. We clicked instantly. I asked her out on a date, we had so much fun. I honestly fell in love with her when I caught a glimpse of her. anyways. We started dating instantly. and everything was fun but we fought so much. at least everyday. We broke up 2 or 3 times a week. we last for about 3 months doing that. She ended up dating someone else. But I ended up getting her back. Our relationship was off and on. But we loved eachother. She cheated. More then once. with my friends. and I dated other people. I never cheated though. We went through so much. and the whole off and on thing went on until September 2011. My parents thought I needed help because I was doing drugs so they sent me off to some wilderness program. I didn't have any contact with her for 2 months. She ended up leaving me for my bestfriend while I was there. I had no idea until I got back in November. The day I got back I saw her. and everything was perfect... I thought we were going to be back together and everything. Turns out she loves my bestfriend. I know there are some other people out there that knows how that feels.. It hurts. bad. Anyways, it came to the point where she had to pick between me and my friend. Well all of a sudden we didn't talk for days. and so I finally called her and it turns out she tried calling me everyday and I guess my phone was messing up and it sent her straight to voicemail. I used to have a voicemail where I was talking but I changed it to just the default voicemail they have. and she thought I was ignoring her. So she ended up picking my friend. I havent talked to a girl really since then. I mean yeah friends that are girls. But I havent had the urge to date anyone else BUT her.. We didn't talk from December until last month. Shes still dating my Friend but they are fighting like me and her used too. Me and my friend started hanging out again so shes always with us. and just 2 days ago. He slept the whole day when we were at his house.. and we started talking. and I finally confessed to her that I still loved her. and that I thought about her everyday.. She said she can't say she stopped loving me or thinking about me because she would be lying.. You have no idea how amazing I felt right then.. well she ended up calling me that night. and last night. and we talk during the day when he isnt around.. but now shes wanting to hang out.. just me and her. Or just with someone that wont tell her boyfriend. and my BESTfriend.. I want to hang out with her.. But I honestly don't want to hurt my friend like this.. Yeah he did it to me. and Ive done it back to him. but I don't want to hurt him. But I don't want to lose her.. so basically. my question is.. what do I do.. should I keep talking to her? or should I just give up on it? I'm lost. :/ Sorry that I typed alot. Just a lot to tell I guess..