Is this love I felt or was it guilt?

my ex and i split a long time ago but we always remained in contact. we still had that chemistry there and we didnt want to lose each other so we remained friends. she went on to date someone else and i tried my best to move on but i just couldnt. bcos of this we fell out alot along the way but we always would find our way back into each others lives. this time when we fell out it was for over a year. i was so affected and sank into depression. i wronged her but i couldnt find the courage to apologize. but somehow we bumped into each other by chance one day and i mustered up the courage to apologize. she was really happy, saying that she had been waiting for the day to come and that she regrets everything that happened, sometimes wishing i was still with her, but the past cant be changed and we should move on. i accepted that. now i feel different. its like there are some days where i feel nothing for her and yet some days when i really miss her and wish we could be back together. what is this feeling? i cant place my finger on it.