I am sorry you felt so down and lonely on Christmas.
If you have a year like that again you might like to try what I have tried in the past when I have found myself in a similar situation.
Some things I have done:
--- volunteered at Community Christmas dinners for underprivileged / homeless people / children's wards at hospital
--- travelled - going somewhere on a plane on Christmas day is fun - you meet other solo travellers, and you make connections with other people who are alone / in transit on the day. I have done this one a couple of times, sometimes on a solo trip to another country, and I have always enjoyed it.
---- have an anti-Christmas - refuse to do ANYTHING Christmassy all season and on the day do the exact opposite of what most people do on Christmas. Certain alters of mine totally loved doing this!

edited to add - if taking a trip to another country a great way to escape the feeling of 'missing out' is going to a country that is not predominantly Christian... Indonesia worked well for me!