Most Helpful Guy
I have seen this question 1000s times in my lifetime if not more. Only one thing heals a broke heart, AND NO IT IS NOT GETTING UNDER SOMEONE NEW, it is TIME. You just have to step back, and reflect on yourself, and get yourself back in working order, then and only then you can move forward. Do not try to make it work or be a side girl, because if you put yourself there, HE WILL KEEP YOU THERE! Guys dream about getting a side girl, that is content being a side girl, because it does not happen. Girls like to "Pee on their trees" and guys like to pretend like they are single No Matter How married they are.
So, just sit down and make a list of stuff you want to accomplish over the next 3 months, and get it done. Take a break from dating, and soon he will be just like every other ex, just another lesson in life, that got you where you are today.
Most Helpful Girl
Well if this is hurting more than helping I would just talk to him about it because odds are its hurting him too. And if he still has feelings for an ex just tell him that you are here for him and that you want to work things out with him... If that's what you want