And what about the lust? Do you think that that too will go away with time?Dandylion - no offence intended here but you are not only stuck in oneitis land but also stuck in sentimentalityland. You need to find new land and stop swimming in circles around your own life-raft of memories. What will satisfy you is allowing time to heal your love scars, allowing her to move on with her life and allowing other female opportunities into your life. Snap out of it now.
After any long term relationship it is hard getting over someone, even if you were the one who broke up. If a relationship breaks up it is usually for a fairly solid reason and only very rarely does it ever get back together and work successfully. Rarely does it actually end in long term satisfaction. Your relationship will never be the same - not to you and not to her especially if you sexted her friends and keep writing endless apologies and pouring out letters of your heart. Its gone. The movie has ended and there is no sequel. There is a fear often that 'wow she was good and the more apart from her the more i realise this and I might not ever find someone else like her again!'. You will find someone better. What you are experiencing is youthful sentimentality for your love, probably a bit of lust too, likely some jealously towards her new boyfriend and also the feeling of enfactuation that comes from wanting something you can't have. If you want something too badly, you won't get it. And most of the time in life, you never even needed it in the first place.
You are looking for a recommendation of what to do and it has been said already 'work on your inner game'. Move on with your life, shut her out of it and find new ground. It will take time, it may even be a lonely quest for a while. Eventually you will stop missing her. You will likely date some girls that don't satisy you and you will be pining for the good times in your past. But you will get better and will start to meet new girls. You will start to meet different girls. You will eventually sooner or later meet even better girls. Then one day... into the future...you will be more than satisfied...and perhaps even your ex will contact you out of the blue and the situation you will be in might be 'sorry, I'm with someone else and it is the best relationship ever' because it truly will be. And you won't care that she has called you up. You won't want to get back with her. The relationship you had with this ex in the fullness of time will be seen as just a 'girlfriend of your youth'. Snap out of your dilema, let your ex get on with her life if you truly respect her and enjoy your freedom of being young and single. Time.