Dear JuneS I send my sincerest sympathy and while we are all different, feel I have an idea of where you are coming from.
I lost my DH 9 months ago and have experienced emotions I never expected. Being a fairly independent person I thought I would cope adequately with going to things on my own and my own company. Not what I expected
DH was ill for several years before he died and in the last 6 or so years needed me to accompany him to ever more frequent hospital clinic appointments in London (50+ miles away) as well as locally. Frequent hospitalisation prepared me after a fashion and I became quite an expert on all things medical so I had the confidence to deal with consultants and nurses, I suppose but I also lived in a sort of denial, refusing to cross bridges until we came to them.
What I am feeling now is not just that I miss him, regret the time we could have spent together,feel the pain of his suffering and quiet courage and regret every living minute that I did not tell him more often how much I loved him.
I have good friends, a loving family and generally see people every day. I also have an affectionate dog, Hattie who gives me a reason to get out of bed, so it is not “just” loneliness, it is an inner loneliness which is hard to put into words. He was the only person who knew exactly where I was coming from, with whom I could be entirely honest about friends and family, who understood me.
Being without him is like an amputation. You learn (I expect) to cope with one arm or limp along on crutches but life doesn’t ever feel like it was before. And you realise that is it, forever.
I am glad to say I no longer have to flee the supermarket in tears because everybody else is in couples, and rarely cry in public, keeping my tears for when I am alone , often because I realise there is something I want to tell him, but can’t.
Sorry to go on at length-your post has opened the floodgates.
Please stay with GN there is so much support and friendship both virtual and real life. It is especially hard if you are unable to get out or see your grandchildren and children but if you can try to be proactive - invite a friend round for coffee/tea/lunch, be the one to initiate the Skype, and if one of your children lives nearby perhaps he/she could help with beds to enable the others to stay over.
We none of us want to seem needy or be a nuisance, but with forward planning perhaps you could see them more than you do now.
But the “inner loneliness”, the silence, or the “nobody to do nothing with” is something we shall have to grit our teeth and get used to 
