Based on how the relationship ended, you may want to get your T to contact him and fill him in instead, if you still want to see him.

Is your motivation for working really hard in DBT for him to take you back as a patient? ...Wouldn´t it be better to meet a new Pdoc and get a " new beginning" instead of going back, to someone who terminated you ( read hurt you alot and whom you were really angry with constantly)

You feel like you have made progress. Why risk it?