So you have come to a dark and lonely pathway. You have been on the straight and narrow for so long, and it seemed like your mutual love for each other would never disintegrate. Well, the truth is, the love should still be there, there just might be a few reasons or things that are holding your ex back from wanting you back. Don't give up hope, there is still a chance of you winning them back for good. Of course, this isn't going to be a nice journey, nor is it going to be a guaranteed one, but if you fight for the one you love, at least you won't be kicking yourself and saying 'what if' in the future!
Of course, these emotions are easier said than achieved. It is hard to even stop thinking about them, so that is something that needs to happen before you go any further. Now I know you are mostly likely predicting every move they make, or everyone they talk to, but believe me, that certainly will not be helping you in the long run. Instead, for the first few days try and focus on yourself, on people you want to meet and things you want to do!
Instead of sulking, focus your mind on the task in hand. The first thing you want to do is to get yourself to a professional. No I am not saying you are going crazy, I mean a relationship professional that can offer you advice. Don't waste your time with free content on the internet, just purchase a few e-books and guides that you think will help and go from there!