Pretty cowardly. At least my exW (not quite 9 years married, 13 in total) had the guts to tell me to my face.
Hope you've got friends who can rally round and support you? Anyone you can call and get drunk with tonight? You'll go through a grieving process for the relationship once you're over this initial shock. Lean on your mates to help you get through it.
Ultimately anyone who can leave a 9 year relationship via a note is someone you're much better off without, but I know that's bugger all consolation right now.