Attendants

Do I invite my ex parents-in-law to my wedding? We became very close after my divorce, and they are loving grandparents to my 6-year-old. But their son, my ex, is a total jerk (they freely admit this and don't speak to him now), and I am afraid they may feel uncomfortable around my new family and old relatives that hate their son. What to do?

How should I send wedding invitations to the girlfriends of my fiance's ushers? Should I invite them and guest so they have a friend to sit with while their boyfriends are at the head table? If no, then won't they be sitting alone? What is the correct thing to do?

My fiance wants to invite his ex-girlfriend to our wedding. He says they are still friends, but they haven't even talked in six months (as far as I know, at least). He claims to be friends with all his exes actually, even the ones that were horrible to him. Is he just being friendly, or does he want to show her he has someone else and show me that other women have been interested in having serious relationships with him too? Am I being totally insecure? If I am, I want to mend my ways before I jeopardize our relationship.

Is it a must to invite each attendant's parents to our wedding?