Mental Illness as a cause of academic disruptions
You don't say where you're located, but assuming that it's in the US, the real question isn't "should you disclose these issues to a graduate school", but rather, "Have you disclosed these issues to your current school and asked for the accommodations to which you are entitled?"

If you're legitimately having problems with anxiety and PTSD and have a diagnosis, the school must make accommodations to help you succeed, per Section  504  of  the  Rehabilitation  Act  of  1973, since you're an adult student, you have to self advocate. That means going to the school, telling them that you have these problems and working out a plan together.