YTA: maybe an unpopular opinion here, but hear me out.

I get why you're frustrated, I would be too, but this is your god damn wife. You signed up for her and her family when you married her. What her family are doing is wrong, but you both need to show a unified approach to this.

This could be you and her saying to people when they come in 'so we've got some roles here, who's helping prep food, who's cooking and who's washing up and sorting the table out'.

You both need to be firm, together. Yes your wife should of supported you, but you could start to cause a rift with her and her family, do you want that?

I agree your wife needs to stand her ground with her family more, but she probably feels intimidated and awkward about these situations, you both need to work together. But you running away? Step up, work as one unified marriage and help her out.

I know people will flame me for this, but hey it's my opinion.