just start talking to her. or get your wingman to talk to her for you. become friends with her. if she acts like she doesn't want to, then back off. if she does want to be friends, maybe see if there might be more. it's not all that complicated. maybe she wasn't wanting to associate with you at first because she did like you but she didn't want anything new right after the break up. who knows. just become friends with her and try not to act awkward. good luck