This bbq I've been invited is a family event, I don't really want to go but people are saying I should go, my W father told me I should go.
Cop1,
If it were me, I'd go to the bbq, but I wouldn't use it as an opportunity to pursue your wife. Her family may be a part of your life for a long time because of your children and I think it's a good thing to remain friendly and connected with them.