I think you done right...sounds like you're prepared for the eventuality that she goes back to her ex...so you're good to go. Hey, if you feel that strongly about her, you gotta fight for it.

Note go your GF: people RARELY change...it's a token gesture that should be viewed as too little too late. my take on situations like that is this: "if you really cared for me, why didn't you change while we were together? i'll tell you why...cuz you're selfish. you're looking to do as little as possible to keep me around and make YOU happy. it is selfish...i'm looking for just a tiny bit of selflesness."