I have been in a situation very similar to this actually and you gotta get out. Like there's guys like this who don't want to be completely honest with the women in their life because they like hedge their bets. So if this current girl he's dating doesn't work out, he can go back to casually dating you just like has been the past 7 years--he might have other girls on a leash just like this. It's the freakin worst. Tells you he's interested and then backs out right after it turns into actual work. (because friendship is cool and all--but it's easy. Relationships are hard work.)
Every time I tried to confront the guy I was with (who is different from your guy so this situation is admittedly a little different) he always turned it into how he was doing me a favor and didn't want to hurt me through committing and then ruining the friendship through dating because our friendship was just so "deep and important to him" and you know what? That was a lie. It was manipulation. Yes, friendship is important, but so is your feelings. It hurts like hell to see someone you like date someone else, and if he doesn't care about that, then he is not your friend.
I'm not saying that he's the same because my guy was uniquely terrible and king of manipulation, but real friends are honest and will ask about your feelings if they have any doubts that you would be jealous. Real friends would listen to you and fess up if they were caught and feel terrible and give you space and distance and not string you along.
And like I don't know his age or anything, maybe y'all are 16 and this isn't as intense as it could be, but I hope you know that it isn't your fault if he lead you to believe you were together and then just...started dating someone else. That's not your fault. That's him being real bad at communication.