Winter and the holidays can be very difficult for individuals who suffer from depression and other conditions. I understand the feeling and have felt similarly in the past. I have since come to enjoy that time of the year whether I am alone or in a relationship or with friends and family. I focus less on the people and more on what I like about it, the holiday lights and snowfall for example. Those sometimes go well with the short days just because of how beautiful the scenery can get, so that's how I have coped with the winter blues.

So sorry to hear about your relationship troubles and depression/panic attacks. I agree with the therapy suggestion and I hope that you can perhaps start to enjoy winter days for their nicer aspects and stay strong enough to get through the rest of the year. Best wishes!