So I know this sub hates when people ask this but..

I have an ex that I think is BPD, not sure but any time I check this site, it sounds like her. 

She broke up with me after catching feelings for someone else, and it was a really nasty break up, mostly after my mental break down and her never being "ready" to talk. Every few months are so, either one of us reaches out. 

She currently has a boyfriend but has asked me to hang out when she was with him. 

Any advice on how to communicate with this girl? She felt unappreciated by me,which I get, but I am in a better place in life with a better work life balance and would like to be her friend at least.