rafichagran is right - will take time and it's understandable. Take good care of yourself.
If you feel very unwell and sad, maybe go to a private counsellor or approach the GP for help and explain you're feeling down - a Social Prescriber might be able to help, they work in many surgeries .
Some people can cope with their own company more than others - some people really find it really very hard and lonely - and the other type of person can't always relate to those feelings.
The luckiest people are those who both enjoy their own company, have hobbies, find things to keep occupied and content etc - AND at the same time enjoy being around plenty of people, big families, grandchildren close by etc etc
If you're someone who likes to be around people and not alone , maybe go to the local library , sign up for a course daytime or evenings, you will meet beautiful people. Find out about volunteering opportunities with families. Find out about walking groups. Part time paid work even. A wee dog (?) or fostering cats before their placement - all these are things that people we know sometimes do, and they provide fun for visiting grandchildren and they tell stories to others ...''my aunt /gran enjoys doing this...etc ''
Maybe a house move, if it's too isolating where you are.
The main thing is to know your family members are happy and thriving, hopefully. And hopefully you can find happiness and thrive too with the right support and encouragement and kindness.
Are you in contact on social media with the family for exchanging photos etc ?
I remember my grandmother found ways to be funny despite her health problems - and her legacy lives on in making us smile decades later. I feel sure it wasn't easy for her always - but I hope that my family will remember the things we encouraged them to do and to get involved in community. Ditch the harsh people who aren't gentle and encouraging.
It's hard to miss people we love - they sound like a really positive addition to the household. Hopefully they visit on special occasions.
One thing we have learned is that there's only one certain thing in life - ie change
Things keep changing and there's always a need to adapt which can be hard and exhausting and sad when it is something we don't want to see changed.