How can I relieve my anxiety and depression?

What a difficult anniversary this must be for you! I'm wondering what the circumstances were around you not being able to see her -- if you mean because she has now passed or because you weren't able to do so before she died. Either situation would be traumatic. Panic could be a reaction to the high stakes of someone you love being hurt, in pain, or kept from you.

First of all, with panic "box breathing" or breathing that involves counting is the first strategy. Inhale for for seconds, hold it for four, then exhale for four. That should relax you some by lowering your heart rate. You can also try the EMDR technique of "hugging" yourself by placing both arms across the front of your chest and alternately patting your upper chess in around a 14 count for each side.  At the same time, you visualize a place and time when and where you felt absolute peace without a care in the world.  Five to 10 reps of doing this while visualizing it in a sensory way (hearing, seeing, smelling, touching tasting) might relax you.

Aside from grief or trauma therapy,  journaling may be productive. The meaning making model of grief pictures it as going through three stages. The first stage is that in which your world becomes inverted, when you're suddenly without your loved one. In the second stage, you learn and adapt how to relate to your lived one with them not being on this earth. It may be through something as simple as reminiscing memories or as spiritual as sensing their presence. The final stage is your own transformation as you evolve into a new person and build a personal legacy inspired by your loved one's imprint on your life.  

The most common model of grief, focusing on sadness, guilt, anger, bargaining and acceptance, encourages people to accept that they may have a variety of emotions that come up and to be gentle with yourself about it.

I think both stages can apply.  Maybe try reflecting and writing about it in a space that feels safe and see what arises for you.