Thanks to you both. It makes a huge difference to hear I'm not alone in this kind of grief.
I'm not on any meds at all. I'm managing well with every day functionality and I as long as I have T to unload on once a week I can cope ok in between. I think this is partly because I can detatch from my emotions (for example I don't really cry, in or out of T). Ironically this had been the hardest thing for me ever emotionally, in spite of much 'worse' things happening to me through my life. I dunno if this has unlocked a lifetime's pain, and I'm mourning more than just this relationship.