Sunseeker, I share your feelings exactly. I lost my DH 6 and a quarter years ago, followed 16 months later by the loss of my younger daughter from very bad PND,which led to her taking her own life aged 33.
During most days now I do try to see other people ,either by volunteering, or by joining in local U3A. groups , or seeing longer term friends.
This has taken me a long time and is good, but the loneliness sets in when I return to my Apartment. ,having had to sell the family home after losing my DH. The Winter evenings are especially long and I long for 'someone to talk to.
My elder DD and family live in the same city, but I still don't get to see them all that often as they lead busy lives ,with 2 children and jobs in the NHS.
My younger daughter left 2 beautiful girls but they live 300 . miles away, so I only see them very rarely.
I try to keep busy as much as possible but nothing makes up for having someone special to share life's ups and downs with.