If you can't be with family, invite some close friends over to share the holidays. Volunteer your time. Many churches or civic groups would be glad of your help. Helping others is a great way to forget your own troubles. Try to avoid alcohol.
Many seniors develop alcohol dependence after retirement or loss of a loved one.
Alcohol is a depressant and will intensify those feelings of sadness. Watch your finances. Most seniors are on a fixed income. Set a budget for gift giving and stick to it. Don't feel guilty if you can't afford to by those grandchildren an expensive gift, its you they will remember not the gifts.