I am a revert and I still live with my non-muslim parents a grand part of the year. They are neither ahlul kitab.
For this reason, it is really difficult for me to respect the law of tahara especially when it comes to food, and it really saddens (and sometimes angers) my dad when I do not want to eat with them (he doesn’t know why but he is figuring it out).
I wanted to know, am I allowed to eat with them for the sake of maintaining family ties even if I know the food or the ustensil used to prepare it has been touched by their wet hands ?

Yes based on secondary considerations it’s ok for you to eat with them