:dancing-banana:
What is the moral principle behind the ecclesiastical law?  If faith and morals are violated, don't go.  If faith and morals are upheld, go.  God's honor first, others' welfare next, your own desires last.  
There are times when one must break civil law to keep Divine Law.  Example, I deliberately ran a red light in order to allow an ambulance on a run to get through traffic.  A man smashes down the door of an apartment and enters for the purpose of rescuing a child from a fire.  It may be that you sin against your wife by refusing to go to a wedding or funeral or social function of her family.  Love for your wife comes before your personal dislike of the event or the people at it.  
Consider others next.  Will your presence scandalise a weak Catholic for whom your example carries weight?  (I refer to those for whom you are answerable to God, not to anonymous people on CI or to a couple from church who just happen to recognise you driving in a procession to the Jєωιѕн cemetery!)  Will your children think it's okay to be both Jєωιѕн and Catholic?  Will your one-time or occasional presence at the novus ordo lead the innocent or ignorant astray?   Last of all, consider yourself.  Will your faith be weakened or will you be seriously tempted to sin?  (Note, I do not say "angered" by sin.)  
If you simply cannot decide, speak to your priest and go with whatever advice he gives, even if you don't agree or even hate it!  Pray about it, first and foremost.  Sometimes God tests us with such questions.  He looks for our loyalty and for our trust in Him. Know that He can be relied upon to work out the details AFTER we resolve to do His Will, no matter what.
The last time I was in a predicament about going to a relative's husband's funeral, (Mike planned for a "rock mass" while undergoing ultimately unsuccessful chemotherapy.), I determined to go and grit my teeth for the good of my cousin who specifically requested my presence.  I booked a flight to Florida from Syracuse, NY for the day before the funeral.  That very night God sent "The Blizzard of 1977" and nobody went anywhere for a week!