Is it permissible for me to remove my hijab and sit with and interact with my unbelieving father-in-law and mother-in-law? And how should I deal with them?

A Muslim woman is permitted to interact with her mahrams (unmarriageable kin) and with disbelievers who are forbidden to her, if she is safe from fitna (temptation/strife). This also applies to disbelieving women, whether relatives or strangers, when there is a need. She must invite them to Islam with kindness while adhering to Islamic rulings.

Regarding clothing, a Muslim woman is permitted to uncover before her mahrams and other women (whether Muslim or disbelieving) what is customarily uncovered, such as the face, head, neck, arms, and part of the leg. However, she is not allowed to wear short, transparent, or tight clothing. The preponderant opinion is that the hijab is not obligatory in front of a disbelieving woman, because it has not been reported that the wives of the Prophet (peace be upon him) and the female Companions veiled themselves from Jewish women or others.

Nevertheless, if fitna is feared from a disbelieving woman—for example, if she might describe the Muslim woman to her male relatives—then no part of the body should be uncovered in her presence.