1) record her threats
2) inform your wife that you have no objection if she visits her parents but don't disturb son school routine
3) wif e threatening husband to put him and his parents behind bars amounts to mental cruelty
4) wife abusing husband amounts to mental cruelty
5) you can file for divorce on grounds of mental cruelty
6) since your child is only 3 years old you would not get custody of your child but can get visitation rights
7)welfare of child is paramount consideration