So, there are things here I relate to.
One: starting to grieve the relationship before it's technically/practically over. Check.
Two: Emotions popping up when you don't expect them to. Check.
The way I think about it, when you've lived under emotional abuse, you are so used to second-guessing your own perceptions and stuffing your own emotions that it takes time before you start feeling your feelings again, and before you start trusting your perceptions again.
I'm so very happy that there is a person in your life that you feel comfortable enough with to start letting those feelings out.