I hardly think that you have abandoned her, as often as you two have contact. It would be very different if you had walked and not looked back, but you are maintaining a high level of contact. You see the girls, go to dinner and parties, until recently worked together, gees, that is not abandonment.
You both have given each other reasons for the distrust. Rebuilding that trust will take time, effort, patience, and counseling.
She seems willing to tentatively try, so try. Slowly, don't ovewhemlm her. You have pushed each other's buttons, part of the anger and hurt that you each have. Not impossible to overcome, but you both are at fault for doing that to each other.
How's the new job and the apartment decorating coming along?
