I know the feeling. For me it's a family member and not my T, but I know that unbearable pull to reach out again, hoping this time it'll be the thing that makes them reply and care. I'm sorry you're dealing with this. Something that's helped (sometimes) is reminding myself when I'm in the moment that the feeling won't last forever; that the life-or-death urge to engage yet again won't last forever (no feelings ever do). It hasn't worked for me 100% of the time, more like 50%, but it's better than nothing! Often it's just a matter of 20-30 minutes until the feeling has passed and I no longer want to reach out.