A lot of people are going to tell you that you just need to get
over him and move on since he hurt you. However, I know you are
thinking that the thought of that is more easier said than done. Of
course it's easy to say you'll move on and forget him but you
really cared for him. So, I want to start off by saying that the
break up is going to cause you some emotional pain, and it will
take some time to get over him. But in time, I really feel you need
to move on and start looking for another guy to date. One reason I
say that is because he broke up with you for another girl, so what
is going to make you think that if you get back together, he won't
do it again? It seems like he doesn't really know what he wants in
his life yet, but it isn't fair it he just toys with your emotions
in his time to decide who he wants to date.
Now, if you do end up back with this guy, I really urge you to take
things slow because you don't know if he will hurt you again, ok? I
know that you care for him, and you're going to want to believe him
when he says nice things to you, and that he won't hurt you, but
you can't ignore the fact that if he hurt you once before, he may
hurt you again. The time you spend being upset about the break up
is just time you're neglecting on hanging out with your friends and
dating other people. You can't put your life on hold for this guy.
If the two of you are meant to be together, then you'll realize
that you want to be together. But, it just seems like he doesn't
know what he wants out of life, and you shouldn't have to wait
around for him to decide he wants to be with you when you could be
dating other people. 
So, as I said, it's ok to be upset about what happened, but in
time, you're going to need to move on and concentrate on yourself
and maybe dating some other people. Dating and break ups are a hard
part of life for anyone to have to deal with it. But, it will only
make you stronger in the end. I know it's not positive at the
moment to see what happened as something for the good but you will
eventually. 
Cheers
