Divorce and Funerals
Divorces don't necessarily terminate relationships with the ex's family. Many people find that their quarrel is with their ex-partner only, and may feel nothing but affection for their ex's parents, siblings and so on. If this is the case, they may well continue to see them regularly, or at the very least keep in contact at Christmas, or on birthdays and other significant occasions.
In cases like this, it is only natural for divorced partners to want to attend the funerals of former in-laws, and it is quite socially acceptable to do so. But beware, no matter how warmly you feel towards your former family, you are no longer officially part of it, and you should not make assumptions about your inclusion. You should not, therefore, head for the family pews at the front, or walk behind the coffin at the end of the service.
The possible exception to this rule is when you are accompanying your small child - perhaps to your ex father-in-law's funeral. In this case, your relationship to the deceased's grandchild may entitle you to 'family status'. If in doubt, discreetly ask a member of the family where you should sit.
Finally, never upstage the blood family when it comes to displays of grief. Your divorce has necessarily placed you at one remove, and you should maintain a tactful and dignified distance. People will understand that you have come to pay your respects, and appreciate your discretion.