How do you go back to being yourself after puttin someone else first and revolving your world around them?

Now that we've broken up I know not to EVER do that again..but how do you stop this cycle. I STILL think of him every day even tho he left me for another girl and I haven't spoken to him in 7 months. I ONLY try to better myself in hopes that we may bump into eachother someday. How can I get past this. 5 years down the drain..only for him to get a gf 5 days after dumping me because 'he needed time'