Hey,
It is okay to miss an ex and it is okay to get over things in your own time, especially seeing as he was your first boyfriend. I think first boyfriends are sometimes the most difficult to get over. Especially seeing as the two of you were together for 7 months, that's a big deal at 16.
It's okay to want to be friends with him but right now I still think you're hurting too much to be able to be good friends with him again. In time it will get easier it's just getting over that initial akwardness.
It will start off difficult going back to being friends but once you're both over the break up it will be easier.
Sometimes people say we're be friends and it never happens the way you planned it because usually feelings still get in the way of you being just friends and one person can sometimes have feelings for the other.
I would suggest speaking to him and finding out why he broke up with you exactly, that can help you to piece things together sometimes and makes things easier to get over, it will be gradual but you'll get there.
PM me anytime
Paige x