Summarize
上梁不正,下梁歪
The ex wife did not have a good upbringing due to her toxic parents who only care about themselves
TS ,you need to have a firm stand, present your feeling to your PIL and wife on spot ,raise your voice to show them you're not a pushover
History may repeat itself, how your first child may receive the bad upbringing from your ex wife and her parents
I think to stop the harassment from your ex wife, cut off ties officially with your son too ,like what your parents said, forget about your first child
You have a toxic wife but then again, you have yourself to blame IMO