josie,
firstly i think all of us ladies are a little crazy.even tho like you say you know whats real and you know you being silly it don,t help.however i think the more you try and be positive and convince yourself things will get easier.
you need to remember that he was young and she was his first serious relationship.i dont think it is until you get older and wiser that you realise what you really want and realise the faults in other people.also men are quite wimpy they just tend to go with the flow,what i,m trying to say is i bet he just went along with everything instead of sorting himself out.
this time its for real,hes older and he knows its you that he wants.surely he would,nt do it for a second time unless he was completly sure of what he was doing.
i went through a similar thing with my best friend.they are stronger than ever and are celebrating their 2nd wedding anv in june.
im pretty sure even though it is mental torture tas time passes by it will get easier.and once your married he will be YOURS.