Diana - the exact same thing happened to me and I was most hurt when a niece whom I'd known since her birth and who spent her summers with me all her life decided to ghost me. It's appalling that she did it as a 24 year-old. But it has a lot to do with them than it does with you. I feel like that's the nature of a divorce. There is reason they say you get married to the family......but it's the ultimate betrayal when all those people you rubbed shoulders with all these years just disappear into thin space.
Hang in there and gain your strength and support from your trusted friends.