It's always a great idea to have one of these.

They usually involve.

1. Who to contact in a mental health emergency. (step by step even better)
2. Times when those people are available to talk/support (for your general use)

1. Warning signs (often ones personal to you)

1. Coping skills to use (distress tolerance skills)

1. General plan following a period of rough mental health (like the xmas your describing)