Lemon, how long ago did you split up? Who initiated the split-up?
I remember feeling severe grief/anguish, I needed to see my t twice weekly at that time.
It is healthy to express the grief/loss/sadness as this aids in the process of grieving. It may seem like an endless black tunnel, but there definitely is a light at the end of it. Being in the dark tunnel is a prerequisite to coming out on the other end.
Allow yourself to feel the grief. If it is consuming you, perhaps put aside a certain time of day for it. Have you tried journaling?
Take gentle care,