Employment Law Questions? Ask an Employment Lawyer.
Unfortunately, under MA law, unemployment benefits are available to someone who loses their job "through no fault of their own." Thus, if you were fired for cause of violating the employer's rule about texting, that is a fault of your own. Even though some other employee was involved and was not fired, that does not mean that you did not violate the rule. Now, if you and the other employee was not fired but also sent such messages, then you have grounds for an appeal in unemployment to argue that the misconduct was not severe enough to warrant termination, since obviously the other employee was not terminated, and as such it is not sufficient good cause to deny you benefits. However, hiring and firing and discipline is up to the discretion of the employer and if they show you violated the rule even if they did not fire the other party, you can still be denied those benefits, especially if they prove you initiated the inappropriate text messages.
You are not entitled to an exit interview under MA law I am afraid. As an at will employee you can be fired for no reason or any reason that is not based only on your age/race/sex/disability/national origin and your only recourse is appealing to unemployment arguing that the misconduct was not severe enough for termination based on the other employee who participated in the texting with you was not terminated.