It was going fine then got awful

It’s kind of long story, my ex broke up with me last week and we stayed friends after. She would message me couple times a day and today she was calling me while she is out of town for work training with new job. Little while we were FaceTiming while she was in her hotel and she was a little flirty and when I mentioned I meeed dinner she said go eat and call me when you are down. 5 minutes after she messaged me why do you want to be friends and I told her I cared abit her still and she would reply no you don’t and then it progressed more. She brought up how I’m still legally married and that I never put the effort of filing for divorce sooner and since I don’t do Facebook I hadn’t gone through my albums and removed pics of us either. I’d been separated from previous ex for 3 years and have no desire to get back with her but my current ex gf kept saying she didn’t believe me, I never hang out with my soon to be ex wife and only talk in regards to our son together. I was little distant in and hesitant with my now ex girlfriend and she felt I wasn’t there for her when she was really stressed about things. I told miss her and I only wanted her and she said no you don’t ,I ruined her life and we can be friends but nothing more and I don’t feel it anymore, then she said she’ll call me back. She called me this morning and evening and was almost like we were back together and of course until just now I never poured my heart to her or anything and didn’t bring up getting back together until she said I toyed with her to try to get back with my ex. Im at a loss and it seems it was such a huge change within literally few minutes , she actually brought up the relationship problems first and that was when I went on to tell her I always loved her and I would fight for her and she said I never fought for her in the past. It would be 6 months together for us. I know many will say cut your losses and let her be happy since I failed her but I’m losing it, I’m not calling her or texting her and don’t want to because we are both hurt, so do I just walk for good or hang back and wait for her to come around?I’m not the begging type but I’ll actually beg for advice here