Ending counselling: how to deal with it?

I've had my counsellor for 3 years now, and she's been great, particularly with understanding my autism and how I think and see the world.

However, she can't work with me anymore because her schedule is changing.

I've not taken the news well. I find myself wanting to email her for reassurance even though our professional relationship is over. Does anyone have any advice for dealing with this?