Hey!
I can understand what you're going through right now. Breakups can be really hard to handle. Past is past and we cannot bring it back what we can do is watch our present and shape our future.
I think you should give yourself some love. You mentioned of how you always compared yourself with his ex which means you lack a little of self esteem and love.
Try some  self love meditations by Agnes Vivarelli, search her on YouTube. That would really help you.
Second, Yes, HE CAN AND WILL COME BACK! I'll tell you something that I applied to my situation as well. Don't worry about it so much. Act as if he's already here with you, live in the end result. Everyone have their days where they feel sad and depressed and have an urge to cry it all out. That's totally normal but don't let it get to you. If crying makes you feel a little light then do it but gather yourself up because you are a STRONG WOMAN! We all are. And we already know what magnificent power our minds possess. Remember if you dwell on a thought too much it might turn into reality. So what will you like your POI already enjoying time with you or him being happily single?
Don't worry it'll all be in your favour. Once you become relaxed and give your mind and universe the time to do their thing, it'll happen at such a crazy speed and in the most beautiful way possible. The 'how' depends on the Universe and the 'it has happened' is on you.
You go girl!
You can do it <3