I've always thought that Blondie has great balance for these sorts of things. One way she sifts the wheat from the chaff is if a supposed friend mentions that they miss you, remind them that the door swings both ways and she can always call you up to go out for coffee. In fact, before you hand out any more explanations, go for coffee first. If they refuse to go to that much effort, you have to ask yourself if they are interested in you or your news.
Every exiting Witness should include things to add to their life, not just take away. If you love entertaining in your home, start getting to know your natural neighbours and have a little "do" at your home. Maybe join a community cooking class. Find some new friends.