Beyond the religious significance, the Christmas season has long been a time of celebrating family or local traditions, of feasting, pageantry, merriment, gift giving, charity and goodwill.
Many of the things we westerners have come to associate with Christmas originated in pagan traditions and iconography that far pre-date, and have nothing at all to do with, Christian faith.
For millennia, various winter festivals were observed in many places, each with their own customs, to bring much-needed warmth, fellowship and cheer to the cold dark days; and to mark the passing of the winter solstice in the northern hemisphere, when the sun once again begins to rise steadily higher over the southern horizon each day. Longer daylight signaled the birth of a new solar year, the turn toward spring and the hope for renewal.
Given what you say about your family dynamic, and what we may deduce of your personal experiences, it isn’t a great surprise that you have no connection to these kinds of ideals. But it isn't too late, you have only to open your mind and your heart to find what other people enjoy about this time of year, take part and make it your own.